A few classes got reworked a bit -- Elemental shaman, Shadow priest and Marksmanship all saw substantial changes to their kits numbers-wise. Some just got flat buffs, like Guardian druid and Protection warrior. And some got their mastery effects played with, like Feral and Balance druids.
For the reworked classes, there is cause for hope. I've been hearing good things especially about Shadow on the PTR, and it sounds like the spec will be in a good place as far as damage goes. This will undoubtedly be good for Shadow priests looking to raid, but that's not the end of the discussion in M+. Unfortunately for Shadow, it still lacks in the utility department. It doesn't bring the immunities or mobility of a mage, and it doesn't have the AoE CC or battle res of a balance druid, so at this point the only thing that's going to get Shadow an invite to high level groups would be astronomical damage. And while I've heard Shadow's damage is good now, I haven't heard that it's better than the specs it would be competing against. There will always be room in M+ for specs that obliterate stuff (like late-Legion Windwalker), but usually damage is even enough across specs that it stops being a differentiating feature, so you focus on things like defensives and utility. And Shadow still doesn't bring much for you there.
Elemental shaman is another spec that got some new talents and buffs to their damage, and Ele was already a strong class in that regard. I don't think the 8.1 buffs will necessarily propel Ele into the M+ meta, but I do think that the dyed-in-the-wool shamans will have an opportunity to compete in high level keys.
I haven't heard much about the Marksmanship changes, which I sort of assume means they aren't earth shattering, but it at least signals an effort by the design team to elevate the spec back into relevance. Maybe it's different in Europe, but in NA there has been a distinct lack of hunters this expansion, and I can't help but think that part of that owes to the current inevitably of speccing Beast Mastery which carries with it a reputation for being fairly simple. Marks has always been the favored spec as far as interesting rotational gameplay is concerned, so if it ends up anywhere close to BM in the damage department I expect to see an exodus in the hunter community.
Guardian druid has languished in BFA so far, both because the spec itself is kind of boring and because it doesn't distinguish itself outside of being a meatshield. The changes to Guardian in 8.1 consist primarily of a fairly big across-the-board buff to its damage and not much else. Vortice di Ursol
was introduced as a talent, which is a nice tool to keep mobs grouped but doesn't really help in getting them grouped in the first place, and Ruggito Impetuoso
was reduced to a one minute cooldown. Buffs are always nice, but Guardian needs qualitative not quantitative changes at this point.
Protection warrior has gotten the community excited recently because it deals insane damage for a tank. 8.1 will take Ignore Pain off the global cooldown which has been a persistent complaint from the warrior community since beta, and it will give Prot more baseline health and armor via a buff to Avanguardia
. These are all good changes, but they don't really address the core issue with Prot right now which is that the spec is a tale of two cities when it comes to taking damage: if the damage being received is capable of being blocked with a shield, warrior is probably the best tank in the game; if the damage can't be blocked (read: magical or DoT damage), warriors get shredded. This leaves warriors in a place where they're fantastic for some dungeons and abysmal in others, and 8.1 doesn't really change that. I expect to see warriors pop up a bit more, but it still won't be a consistent presence in the meta.
Balance druid is getting its mastery changed up a bit to include
in the spells affected by mastery, and this should have a positive effect on the spec's single target damage. Balance is already a popular pick in M+ because of its outstanding utility and defensives, and if the 8.1 mastery changes make the class a pumper on boss fights while also dealing strong sustain damage on trash packs, you can expect to see this spec all over the leaderboards.