I think you guys are looking too much into this, it is possible that it's not going to be kept exclusive but if you compare it to bioshock's first boxart that does not say exclusive to the pc and xbox360 and the real one where it does say it you can see that they don't nesscarily put that label on there
http://www.destructoid.com/final-bioshock-boxart-love-it-or-hate-it--32476.phtml
http://cgi.ebay.com/Bioshock-for-Xbox-360_W0QQitemZ300280319663QQcmdZViewItemQQptZVideo_Games_Games?hash=item300280319663&_trksid=p3286.c0.m14&_trkparms=72%3A1234%7C66%3A2%7C65%3A12%7C39%3A1%7C240%3A1318%7C301%3A1%7C293%3A1%7C294%3A50#ebayphotohosting