Bioshock is a really good game, but Oblivion is better for sure.  I think my prediction is pretty good, regardless of the install base.

Very low. Its an old game which was touted as an exclusive for too long so all who really wanted to play it have done so already and others (like me) had accepted the fact that they would most likely never play it. Add that to the immense competition from big budget exclusives like LBP and R2 in the same season and you have a very mediocre seller.

WW 150k max, a FPS in Japan (although Bad Company did alright). Europe, will be okay and America better adding up nicely. then it will fall. It won't be huge but they'll make some of their money back, just a year is too long. It better not take a year for Star Ocean 4 to come out on PS3 after 360.

i think around 400WW Life time..
and around 80k for First week WW

million seller by mid 09

200K lifetime

Also consider this...IT WILL BE REALEASED ON THE SAME DAY AS LBP

I think it will struggle to become a million seller.

I think the game will not sell that well. I myself was really looking forward to this game at first, like I anticipated Mass Effect to be a good game. Then the suits stated this game certainly wasn't coming over to the PS3. Meanwhile I played Mass Effect on the 360 and didn't really like the game overall, then there were Bioshock 2 rumours for the PS3 and so I checked out all the Bioshock story telling scenes and some gameplay footage over at youtube to see if the game really was worth the hype and wait.

The game looked indeed interesting, but of course I now lost all interest in this game (no surprises or real wows left for me). One sale less here at least, I think due to their PR (shooting themselves in the foot) they don't deserve to sell many copies on the PS3. And then I hope they learn from their mistake.

...Many have played it on Pc, even me.
But still,Im gonna get this, if its something like 49€.
I expect....first week 300-400k,lifetime about 1,5m-2m