First, I want to say I see what you are thinking, and I understand why.

Imo I think the game should be heavily worked on until the ps3 release. If we can show people how much it has changed before then, and can promise continued change after ps3, I think that will be the best course of action. Also Like when RoZ (first XI expansion pack) MUCH content came with it, and I think if SE continues to give us regular content but is also working on a full fledged expansion pack, that will be the best course of action.

RoZ offered:
"Fixed" SMN (no more just eles)
new regions
new end game area
new jobs
new content/battles
new mission line
continued nation missions
level cap raise? (i think this may have been prior to RoZ, or done in steps, I dont remember fully)

Anyhow if we can have basic additions done up until ps3, and then have a real expansion, I think that would be best.