There is till an unknown number of digital sales to consider, although i doubt it will be very high.
i don't think the port was too expensive. they probably worked on a multiplat version from the getgo anyway.
i suppose they always knew it would realease on the PS3 they just could not disclose it for the duration of the timed exclusive contract.
i wonder how much money they got for timed exclusivity. in the end microsoft might have payed for the PS3 version 
“It appeared that there had even been demonstrations to thank Big Brother for raising the chocolate ration to twenty grams a week. And only yesterday, he reflected, it had been announced that the ration was to be reduced to twenty grams a week. Was it possible that they could swallow that, after only twenty-four hours? Yes, they swallowed it.”
- George Orwell, ‘1984’
