Yeah, Tom has said that they would like to bring out the PS3 versions if possible but that's not something they're worrying about right now since they're still focused on getting us the games at all. If they don't manage to do it, you won't really be missing much unless the platform is a problem; The PSP version has all the same content as the PS3 port (although the latter has extra goodies like wallpapers and the OST bundled in) and the PC versions still look the best out of all three with a couple of flourishes not found in any other release, like the sweet dynamic lighting.
3rd's got a decent chance if SC does ok, since 3rd has less text than SC and can come out for the same platforms.
Do note that FC-SC form a good unit, and actually if you care about unfinished plot threads, 3rd would be a worse game to end on than SC. Sora no Kiseki is technically a "trilogy" but the kiseki series is really three parts (not counting Sen, which I haven't played yet): 1. FC-SC 2. 3rd, which has its own plot, additional backstory and info on the FC-SC characters, and hooks for later games 3. Zero-Ao
It's better than the PSP, but I think it becomes a lot more questionable if you try to project about when Zero and Ao could be expected based in even a best case scenario. I mean, Zero and Ao are longer than SC and SC is going to clock in at over 3 years, so Ao could very easily be 8+ years away at the current pace. Vita might be okay now, but by then?
Really, whenever I think of it like that I honestly feel pretty awful about the odds of Zero and beyond even with excellent sales from FC and SC. I'd love for nothing more than to be proven wrong, but it (the platform situation) definitely seems like the absolute biggest challenge moving forward IMO.
xp1337: Don't you wish there was a spell-checker that told you when you a word out? GotD (219/384) Melee v FFX