Trying to improve the raiding experience for a wider range of players [cause dropping over 2 million subscriptions hurts], Blizzards wants to fill the gap by developing a new type of Raid for the next major content update: Flexible Raiding.
In patch 5.4 they will make their first attempt to provide a better experience to raiders category by introducing a new mode of raiding.
The Flexible Raid system (currently in development) will include a new difficulty somewhere between Raid Finder and Normal, that will be available for premade groups of 10-25 players. So if you have 13,17 or 22 friends online they will all be able to join it. The system is designed to scale depending on how many players join the Raid. For this new raid system no matchmaking is available, but there is the option to invite Real ID or Battle.net friends cross-realm. There is no item level requirement (so you decide what gear player needs to enter your mighty group).
With the launch of a new Raid mode there will also come a new item level. The loot inside Flexible Raiding will also be somewhere between Raid Finder and Normal difficulty, and will use Raid Finders’s “per person” loot system, specialization choices and bonus rolls.
The new difficulty has a separate Raid lockout allowing players to take part in all three if they desire. Also, portions of “Glory of the Ogrimmar raider” raid meta-achievement will be completed in Flexible mode.
Keep an eye on PTS realm cause this mode is getting close.