I think Flex Raiding will almost certainly fit perfectly for all those guilds looking to get into raiding. Why bench people without to? The sole requirements will be which you have enough tanks and heal; dps can fill the remainder only the way it’s now. Individual loot is best approach to handle it too, but I’d really like to view the tools tradable between members with the raid. The raid leader can facilitate that, in the same way master looters do now.
Will it replace normal 10-man raiding, possibly. That’s far into your future, though. Blizzard will need to observe how this grand experiment computes before they will make that call. They’ll develop the information and statistics to accomplish this. Realistically, I can not see this killing the 10-man raid guilds, but expanding with them. From edinburgh, guild/raid leaders can make and find the raiders they want to take on their 10 man runs.
What it really won’t do is replace 25 men raiding, either on normal or heroic. The progression raiding guilds have nothing to fear there. World Firsts will still happen with different fixed difficulty and really, more power to those players and guilds.
Flex won’t replace LFR because LFR was made if you have no fascination with investing a raid schedule in the least. LFR is great for you at all like me and like every my WoW buddies that have busy lives and many interests besides wow gold, but nevertheless fork up our money each month and also see the many content. Frankly, whenever they removed LFR I’d quit. I’m just never planning to do regular raiding, but I resented for a long time the inability see the culmination from the story in each Xpac and i am sure not likely to pay Blizzard to the ever again.