Just seen an blue update on the future of raiding:

We’re continuing to refine the raid progression paths in Cataclysm, and we’d like to share some of those changes with you today. Please enjoy! 

The first of the refinements being made is that we’re combining all raid sizes and difficulties into a single lockout. Unlike today, 10- and 25-player modes of a single raid will share the same lockout. You can defeat each raid boss once per week per character. In other words, if you wanted to do both a 10- and 25-person raid in a single week, you’d need to do so on two different characters. Normal versus Heroic mode will be chosen on a per-boss basis in Cataclysm raids, the same way it works in Icecrown Citadel. Obviously the raid lockout change doesn’t apply in pure Icecrown terms though, as this change goes hand-in-hand with a few other changes to raid progression in Cataclysm. 

We’re designing and balancing raids so that the difficulty between 10- and 25-player versions of each difficulty will be as close as possible to each other as we can achieve. That closeness in difficulty also means that we’ll have bosses dropping the same items in 10- and 25-player raids of each difficulty. They’ll have the same name and same stats; they are in fact the exact same items. Choosing Heroic mode will drop a scaled-up version of those items. Our hope is that players will be able to associate bosses with their loot tables and even associate specific artwork with specific item names to a far greater extent than today. 

Dungeon Difficulty and Rewards 
10- and 25-player (normal difficulty) — Very similar to one another in difficulty; drop the exact same items as each other. 
10- and 25-player (Heroic difficulty) — Very similar to one another in difficulty; drop more powerful versions of the normal-difficulty items. 

We of course recognize the logistical realities of organizing larger groups of people, so while the loot quality will not change, 25-player versions will drop a higher quantity of loot per player (items, but also badges, and even gold), making it a more efficient route if you’re able to gather the people. The raid designers are designing encounters with these changes in mind, and the class designers are making class changes to help make 10-person groups easier to build. Running 25-player raids will be a bit more lucrative, as should be expected, but if for a week or two you need to do 10s because half the guild is away on vacation, you can do that and not suffer a dramatic loss to your ability to get the items you want. 

We recognize that very long raids can be a barrier for some players, but we also want to provide enough encounters for the experience to feel epic. For the first few raid tiers, our plan is to provide multiple smaller raids. Instead of one raid with eleven bosses, you might have a five-boss raid as well as a six-boss raid. All of these bosses would drop the same item level gear, but the dungeons themselves being different environments will provide some variety in location and visual style, as well as separate raid lockouts. Think of how you could raid Serpentshrine Cavern and Tempest Keep separately, but you might still want to hit both every week. 

We do like how gating bosses over time allows the community to focus on individual encounters instead of just racing to the end boss, so we’re likely to keep that design moving forward. We don’t plan to impose attempt limitations again though, except maybe in cases of rare optional bosses (like Algalon). Heroic mode may not be open from day one, but will become available after defeating normal mode perhaps as little as once or twice. 

In terms of tuning, we want groups to be able to jump into the first raids pretty quickly, but we also don’t want them to overshadow the Heroic 5-player dungeons and more powerful quest rewards. We’ll be designing the first few raid zones assuming that players have accumulated some blue gear from dungeons, crafted equipment, or quest rewards. In general, we want you and your guild members to participate in and enjoy the level up experience. 

We design our raids to be accessible to a broad spectrum of players, so we want groups to be able to make the decision about whether to attempt the normal or Heroic versions of raids pretty quickly. The goal with all of these changes is to make it as much of a choice or effect of circumstance whether you raid as a group of 10 or as a group of 25 as possible. Whether you’re a big guild or a small guild the choice won’t be dependent on what items drop, but instead on what you enjoy the most. 

We realize that with any changes to progression pathways there are going to be questions. We’re eagerly awaiting any that we may have left unanswered. To the comments! 

This solves so many design problems in one go:
– Ever since WOTLK came out people have been abusing the seperate 10 and 25 man raid lock outs to effectively double their loot chances
– As both raid sizes share the same loot it won’t be possible to trivialise 10 man raid content by outgearing it with 25 man gear
– Gear level inflation will be controlled as there are effectively only half the amount of gear steps needed
– Still benfits 25 man raids by giving them a higher chance of getting loot, if there are 2 drops per boss in 10 man there could be 6 drops in 25 man giving them an advantage.