I do see a great chance in the Cataclysm raiding system, mainly because I'm not happy with the current state. I do suffer from burnout because I had to run ICC 10 man to be prepared the best way possible for progression in ICC 25. So I appreciate this new approach.
But Blizzard has to solve a lot (and by a lot I mean A LOT!) of problems and I do admit that we cannot look at Blizzard plans from our WotLK point of view. If you adapt the WotLK raiding system to the Cataclysm system it would result in a disaster. And just because I love WoW I hope that Blizzard can pull it off.
Guilds will suffer from the change as they did with the Vanilla -> BC switch. It will mostly not be the top 500 guild (well maybe more let's say all guilds who managed to get all the WotLK meta-achievements and/or the TotGC 50 tries left run), they will do their stuff just as they did in the last 5 years. It will be the guilds with less progress but those guilds are the majority of the raiding guilds and that will lead to a great shift in the way we play WoW.
In my very own guild (8/12 heroic) a lot of player say that they will switch to 10 man raiding as soon as Cataclysm gets shipped. I remember the problems my guild had when the majority of our members reached level 70 and it almost collapsed but we managed to start raiding successfully again because we had no alternative; doing 25 mans was the only way to go.
But with Cataclysm there is this alternative we hadn't at level 70 and I do believe that we are not getting out alive this time. Just to many player are not willing to bear those few bad players anymore that almost every guild has.
So yeah, we will see a lot of guilds disbanding.
Another problem (but one Blizzard can solve because they did in the past) will be the amount of content you need to provide to keep player with more playtime interested. They did so in BC but didn't in WotLK. So again it is dangerous to adept Blizzard plans for Cataclysm on the WotLK raids. So raiding only one format must provide content for 3-5 nights of raiding.
I guess we have to wait for more info on the topic from Blizzard and see the changes with our own eyes. Perhaps the beta will help us to make up our minds.
Only the future will tell :P .