Alcibiades
Plant Geneticist
Point taken, but the fact remains you're still going to have to go back to the old game, add a secondary viewpoint, re-play the entire game to check for any discrepancies, probably re-do most cutscenes and then re-release, all for not very much return. I doubt everyone that bought the original of a game would buy the 3D version "just because". Sure it'd be possible, just fairly pointless
Tbh, people are willing to spend their money on all sorts of pointless things, and I expect that you could make money off re releasing games as 3D. (Think Gold/Platinum/Special Edition games)
Now, the companies will probably not do it since, as you say, it is time consuming and you could make more money doing something else.
That being said, I won't be buying or even considering buying a 3D TV for a few more evolutions of the product since I rarely consider it wise to invest in the first generation of any new technology; but it will be very interesting to see where, and how, the technology develops.