I think that the next game will be the last(in terms of presenting a new story, and expanding the plot), because we only have 9 years of Compilation. They take 4 or 5 years to create a game of quality, so... 4 or 5 years for the next PS3 game with Genesis, and 4 or 5 years for the remake of the original one. Then it's over.
About the Compilation in general, I like that FFVII's universe is being expanded, with new characters and new stories. But they have to be careful to not "saturate the Compilation with so many new characters that will essentially alienate the purpose of creating the Compilation", like Mako said. And unfortunately, this seems to be the direction the Compilation is going.
I mean...
First we had AC. Something that was connected with the original story, showing what happened with the original characters after Meteor, and Cloud's internal conflict, culminating with the Cloud-Sephiroth rivalry.
Then we had BC. A game that IMO, was connected with the original story, because it showed the beginning of Avalanche, and how it all started.
Until now, everything is fine.
But then, comes DoC. A game showing many new characters(the Tsviets, Shalua, Genesis, etc), and concepts(the Protomateria, Omega, DeepGround, etc), that have nothing to do with the original story. Hell, they even "replaced" Aerith with Shelke(the new member of Avalanche).
And then we have CC, a game created with the main purpose of explaining who is Genesis, and why he appeared in DoC's end. Yes, I know that CC is Zack's story, but that's just a bonus. Genesis' story happens in the past, and they needed a main character who lived and fought before FFVII's time. Zack was the perfect choice.
And finally wee will have the next game, where Genesis and Weiss will, probably, be very important to the plot. Weiss and Genesis... Two guys who have absolutely nothing to do with the original story of FFVII.
So IMO, the Compilation started to lose it's "roots" after DoC's release. Deep-Ground and Genesis' existence, started to carry the story to another direction, one that I'm liking until now... But I hope they don't lose themselves, by going by this new direction.
But anyway, this is just my opinion. Feel free to disagree.