This expansion has seen a lot experimentation in endgame. Some of it has been good, and some of it has been bad. After thinking about what I liked and disliked in Wrath, here is the first part of a plan that I would love to see in Cataclysm.
1. The first Tier of raiding opens 3 months after the launch of Cataclysm.
I greatly disliked the "rush" to get to Naxxramas. Levelling, normal dungeons, and heroics, were all severely diminished by the fact that Naxx was available so early. By delaying the opening of raiding for a few months, that gives everyone time to explore all the other facets of the game at leisure. As well, normal dungeon and heroic loot won't get obsoleted so fast.
2. 5-mans only drop blue gear.
I think that dropping scarce epics was a mistake. For one thing, the one epic drop obsoletes a lot of the other blue gear that drops. For example, [Red Sword of Courage] was strictly better than all other 5-man tanking weapons. Second, it allows you to start the raid game at lower item level. Finally, I think everyone skipped past blues and into epics too fast.
3. Heroic 5-mans drop an 8-piece class set.
I miss the dungeon sets of Vanilla. Dropping an 8-piece set gives something for people to collect, a reason to run many heroics. Ideally one piece would be dropped by the end boss of each heroic instance. There would be a version for each class-role combination. The set would have 2-, 4-, and 6-piece bonuses.
As for looks, I think a good motif would be "greatest hits from Tiers 1-6". That way it's a nod to nostalgia, while reusing artwork. For example, the Ret paladin set might be "Reforged Judgement", or the Rogue set could be "Restored Bloodfang". Alternatively the set could just use the blue Cataclysm armor artwork.
4. Heroic 5-mans do not drop badges at the start.
There is no need for badges at this point in time. Later, once raiding gets underway, badges can drop.
Edit: After thinking about this a bit more, it occurs to me that Heirloom gear will still need to be purchased. Heroics could drop Valiant Badges, but the only things for sale at this point will be the Heirloom gear. I think that Badge gear fills a hole when it comes to the scarcity of raid drops, but since random heroics can be run extremely often, badge gear is not necessary for 5-mans.
5. The Daily Heroic rewards 2x Champion Badges. A maximum of 8 Champion Badges can be earned each week.
There is a weekly cap on Badges so that people do not have to log in every single day.
6. There will be a maximum of 3 epic items available from professions. No weapons. Maybe belt and bracers and a ring. Recipes for these items cost Champion Badges. As well, these recipes require an ingredient which costs Champion Badges.
Here's a little tidbit to make crafting interesting. These recipes should be highly valued, as they are pretty much the only epics in the game (other than maybe a couple epics from exalted faction reputation). I like the way Primordial Saronite has worked out, and I think it's a good model to use for professions at the start of the expansion.
7. Reputation grinds use the "Tabard" model of Wrath.
I really like this model. It's flexible and easy to understand. As well, wearing a faction's tabard really drives home the idea that you are working for that faction, or accomplishing deeds in that faction's name.
I think this model will give people a solid foundation to start raiding. They can take their time leveling, collect sets in dungeons, and will enter the first tier of raiding with mostly blues and maybe one or two epics. I think that the first point is key, though. If Cataclysm launches with raids, a vast amount of content is going to go to waste.