Keep raising the level cap but crunching how much experience is required per level as you do. This is the approach WoW has historically taken. But as this happens, levels start to seem meaningless. You gain them ultra-quickly, and only a smattering of them actually introduce new abilities or other perks. It also means that you blast through the leveling content at such a pace that you never finish individual zone stories; you only finish a small portion of an area before you have outleveled it and are ready to move on.
The spell called "spiritual projection" or "astral projection" brings the caster to the Twisting Nether instead of the Shadowlands; and the Twisting Nether is also referred as "realm of ghosts". However, both planes don't appear to be related, as Outland is floating on the Twisting Nether, but the Shadowlands can be reached in Outland in The Burning Crusade.
Adventurers entering the Shadowlands will find the realm of the dead in disarray. In the natural order of things, souls are sorted and sent on to an afterlife realm appropriate to the lives they lived, but starting around the time of the Burning Legion's third invasion of Azeroth, all souls who have perished—including the innocents slain at Teldrassil—are being funneled directly into the Maw. The Shadowlands are starving for anima even as the Maw continues to grow from the glut of fresh souls. Sylvanas Windrunner has been seemingly perpetrating acts to bring about great amounts of death and destruction. In partnership with the Jailer, they have been working toward a common end for some time.
Since this was an early questing experience and not an endgame one, I didn't get much sense of how Covenants—Shadowlands' new Order Hall, Garrison, or War Campaign-like systems—work. Neither did I have much time to dive into the story, though I saw enough to know that, if you like the flavor of the recent WoW expansions, you'll probably like this one, too. (I, for one, am glad we're going to get a brief respite from the Alliance vs. Horde war storyline.)
That might seem odd or negative to those who aren't currently playing WoW, but it's actually something a great number of today's WoW players have been asking for. As the levels rose in this 15-year-old game that frankly wasn't designed with a 15-year plan in mind, Blizzard encountered all sorts of frustrating game design problems that players have been cranky about, too. The WoW team has already crunched player stats like health and mana down on multiple occasions as a way to postpone fully solving the problem, so this is the culmination of something that has been underway for a few years now.
It's hard to get a sense of an entire World of Warcraft expansion from 30 minutes of play. In my short demo, I recreated my main (a Beast Mastery Hunter) and played through the introductory quests from the Bastion zone, a heaven-like plane from Azeroth's afterlife. The minute-to-minute gameplay very much followed the formula of modern WoW questing, with a variety of tasks like challenging specific enemies to duels, helping craft things in timed minigames, and of course, killing 10 rats (well, not rats, but they might as well be).
Keep raising the level cap with no changes to the leveling experience up to that point. This leads to ever-lengthening leveling ramps that make it extremely difficult for new players to get to current content. That's because each expansion adds another several dozen hours to how long it takes to get from the start to being able to play with friends in the endgame. (Final Fantasy XIV has this problem to some degree, even though it's nowhere near as old as WoW.)
The Realm of Shadows may be the same World of Shadows as the one that becomes visible when a [Elixir of Shadows] is consumed. It may also have something to do with shadow magic and shades. Death knights, necromancers, and undead as a whole share a strong connection with the Realm of Shadows from many hints that can be seen in-game. In the death knight starting zone, death knights are given the task to enter the Realm of Shadows in order to gain their Deathcharger. Later on, death knights are eventually able to learn the ability [Raise Ally] which pulls their ally's spirit back from the Realm of the Dead and forces it back into their body. Upon doing so, a buff is applied to the player stating that: "A touch of the spirit realm still lingers..." This shows that death knights and necromancers both have a connection to the Realm of the Shadows/Dead to perform necromancy which furthers the idea that they actually are drawing their magical power from it.
During the Burning Legion's third invasion, the Knights of the Ebon Blade traveled to the Shadowlands to acquire the Aggregates of Anguish, five tormented essences of powerful souls - Admiral Proudmoore, Soulbinder Nyami, Grand Empress Shek'zeer, Grand Apothecary Putress and Archmage Arugal. Salanaar required these to conjure the Steeds of the Damned for the order's new Horsemen.
Blizzard hasn't talked about what it plans to do after Shadowlands. I speculate that the longterm solution would be to do this every expansion—so in the next expansion, Blizzard might move Battle for Azeroth into the multitude of choices for new character-leveling experiences and push level-cap characters back down to 50 to start whatever expansion comes after Shadowlands—an odd hybrid of traditional MMO and a seasonal model common in plenty of modern multiplayer games.
As always, though, Blizzard really delivered on the art front. Bastion is striking, with big, beautiful skies, banners realistically waving in the wind, and fascinating characters, like a humanoid, owl-like race that inhabits the zone. Blizzard artists told me that they plan to support RTX raytracing, as well as new kinds of real-time lighting, in the expansion. I'm surprised by how good modern WoW looks on a high-end PC these days, given that it originally came out in 2004, and it looks like that work will continue.
Furthermore, upon the Lich King's death he even spoke of "Seeing only darkness before him" while Sylvanas Windrunner said the same in Silverpine Forest after being risen from the dead by the Val'kyr. This may hint that because undead, death knights, and necromancers are connected to the Realm of Shadows when they die (again) they actually become apart of the Realm of Shadows and are forced to wanders in its dark mists for the rest of eternity. If this is so, then it can also be implied that when a death knight is given his/her own personal runeblade, the runeblade is actually used to bind the individual to the Realm of Shadows in mind and body, making it impossible to ever be rid of the death knight curse. In Howling Fjord, players are even able to witness the Lich King himself standing within the Realm of Shadows with two Val'kyr. The idea that necromantic magic and death knight runes drawing power from the Realm of Shadows itself is not yet proven, but it is heavily supported by in-game quests and lore.
Claim a covenant's power: players will be called upon to forge a bond with one of four covenants that rule Shadowlands' new zones, setting the tone for their journey through the expansion with a full covenant campaign. As they level up, they'll get new abilities based on their choice, including class-specific abilities for each Covenant—as well as developing soulbinds with specific covenant members, which grant them access to that character's specific traits and bonuses.