How big would these rooms be? Because while I don't agree with the cold accounting calculations that lead to startup mgmt. preferring open office plans, I understand that it truly maximizes empty space. To guarantee an office for each employee- I'm not sure how it can be sustainable unless you're working in an office park with enough cheap space.
Doesn't need to be 1 per individual, can group together small groups. Most "open plans" tend to waste lots of space on excessively wide desks, meeting areas, decorations, etc.