I've been debating how to structure this post. Should I discuss what I see wrong with the current endgame, and then look at solutions? Or should I present a plan, and explain what I think is wrong with the current endgame through the lens of that plan? I've chosen the latter, but I'm not sure it's the best choice.
I think the pendulum of the raiding endgame has swung a little too far. It needs to be brought back towards Vanilla/TBC. Not all the way, because that would be just crazy. But I think some of the desires and ideals of this current endgame have just not worked out the way they were intended, and should be jettisoned.
So this is my plan of what, as of this point in time, I think the ideal endgame for WoW should look like.
1. One Raid Size: 15-man
This is going to tie in with Point 2, but with two raid sizes there are just too many variations. 25-mans are dying because 10-mans are so much easier to organize. There are conflicts over abilities like Chain Heal. You cannot guarantee a full complement of buffs/debuffs in 10-man. You can't even assume that there will be one of each class.
15-man is a good compromise. It's only a bit larger than 10-man, keeping down administrative complexity, but enough that a raid will carry a good cross-section of classes. You can tune it for 2-3 tanks, 9-10 DPS, and 3 healers. That makes it match 5-mans. We can have three tank fights once again.
2. Three Difficulties: Easy, Normal, Heroic
I think it's pretty clear that raiding needs an Easy difficulty setting. Right now, Blizzard fudges it with buffs and nerfs to old content. Heroic is necessary to challenge the Royalty and Aristocracy guilds, while Normal is needed for Gentry and Bourgeois guilds.
But when you go lower than that, or when you try to turn raiding into transient content via pickup groups or an automatically generated group with a Raid Finder, you're going to need an Easy setting. I don't really want to see Normal mode gutted like BWL and BoT were.
To go back to point 1, right now there are 4 permutations of raids: 10-Normal, 10-Heroic, 25-Normal, 25-Heroic. If we introduce a third difficulty setting, that would make 6 permutations. One raid size brings the number of permutations down to 3, making balancing even easier for the devs than the current situation.
3. No Valor Points/Badges
If you want raid loot, you kill bosses. No boss kills, no loot.
All these point systems just warp the game and force people to do content that they aren't really interested in. It even spoils the lower levels of content with bored people just in it for the points.
If you want to have Justice points, and have the previous tier of gear available on a vendor, that's different. But the current tier of loot drops from bosses, as it did in Vanilla.
4. Only One Item Level of Gear Per Tier
Honestly, what has multiple item levels per tier really gained us? Pretty much just massive stat inflation across the board, and non-iconic tier sets. Royalty and Aristocracy guilds enter the next tier in higher level gear anyways. Their gear only increases by one jump, just like everyone else. If everyone started at the same item level, it really would not make much of a difference.
The major counter-argument to this is that heroics need the higher item level to attract people. I don't think this is the case. For the majority of guilds at this level, it's really about the challenge, bragging rights, and recruiting.
If this had been the case in Cataclysm, we would have seen:
BoT/BWL = i359
Firelands = i372
Deathwing = i395
I think that's a much more sensible scheme than watching Deathwing loot top out at some crazy number.
5. Quantity of Loot Varies With Difficulty
Easy drops 1 piece per boss. Normal drops 3 pieces. Heroic drops 5 pieces. Additionally, Tier Tokens don't drop in Easy, only Normal and Heroic (1 token in Normal, 2 in Heroic).
That gives lots of incentive to move into Normals and Heroics. You don't want people to wallow in Easy. If 1 piece is absolutely too low, maybe 2/4/6 would be better.
Right now, gear is a bit too easy to come by. Pushing the scarcity pendulum back towards Vanilla would make upgrading more interesting.
6. Flexible Lock-Outs
I like the current Normal mode lockout system. I think the extra restrictions on Heroic mode are proving to be unnecessary. As long as each character only kills each boss once per week, I think it's fine to allow people the maximum flexibility when making groups.
Don't bother with gating Heroic/Normal with Normal/Easy mode, let the guilds go nuts on their chosen difficulty from the start.
7. Separate Achievements More
Right now, I think Achievements are too focused on Heroic mode. What I would do is have the mount achievement be more aimed at Normal mode. The mount achievement would require beating the instance on Normal, and doing all the "special achievements" for each fight on Normal or Heroic.
At the moment there's a bit of a conflict between Heroic mode and the special achievements. You can really only do one or the other, and the fact that Heroic mode offers better loot often makes the special achievements a one-night thing. I think that making the mount achievement doable without Heroics would make it easier for Gentry and lower Aristocracy to get. It would separate out the rewards more, rather than clustering them at the very high end.
The title achievement would require doing the instance on Heroic mode. If the final boss is going to be a "super-fight", you might want two titles or rewards, one for killing 6/7 Heroic, and one for killing the end boss on Heroic.
Edit: This didn't come across quite the way I intended. In the current endgame, there are essentially two Meta-Achievements with rewards for a raid tier. Both Metas require heroic modes. I'm advocating having one Meta for Normal modes (the one with the "special achievements") and one Meta for Heroic modes (basically beat the instance on Heroic). Each Meta has a reward, but what the reward is doesn't really matter. If you want to reserve the mount for the Heroic Meta, and have the title for the Normal Meta, that's fine.
But the basic idea is to have one Meta-Achievement for Normal mode, and one Meta-Achievement for Heroic mode.
So those are my suggestions for endgame. A lot of the current innovations in raid administration (size, lockout, difficulty) are kept, but gear moves back to a more old-school Vanilla style model.