Hopefully they can bring back some BC and Vanilla raids into this as well.
Vanilla raids can be soloed, and almost anything up to WotLK can be stomped in a 5-man.
It would be nice to be able to queue up for a nostalgia run, but if it has to fill up to 25 people, there's not much point. You won't even be able to get more than a few spells off before the boss is dead.
They might be hoping its added for lower level toons to do level appropriate raid from LFR.