I hope to god that that's not the case. If they're using the same engine, I'd kind of assumed that it would be still playable on FB-compatible computers. One of the best things about FB is that it's efficently coded imo, and very scalable. I'd be concerned about map sizes, and AI troops, but would still be happy with online maps and a mission builder.

Could we get a developer hint at specs? No-one's going to hold you to it...