WoW has seen a shift in raid sizes, from 40-man to the current 10- and 25-man difficulties, but one size does not fit all. What about the in-between raids? Those nights players can't fill a 25-man or have a few more than 10 show up one night? Flexible Raids look to fix that.
The challenge level is designed to scale depending on the number of raiders present, and the system allows a switch from week to week with adjustments made automatically. And with a new challenge level comes a new ilevel that falls between Raid Finder and Normal quality.
What about loot? So far, it seems that the Raid Finder "per person" looting style will be in place to keep things running smoothly for raid leaders. The good news is that Flexible Raid difficulty has a separate lockout from both Raid Finder and Normal difficulties, allowing for participation in all three if you're up for it.