I doubt we will see the cars lie there pitifully after they have rolled over. To be honest, roll over is something I am really only interested in for the rally driving modes.
I am betting that during races, cars that roll over will be automatically righted and put back on the middle of the track, probably blinking a couple of times in that familiar 'you screwed up and the video game is fixing you and you have no control over this 3 or 4 second process' kind of way.
Honestly, though, if you want roll over to end your race (as it really ought to) in a realistic manner, there is an easy fix. After you roll over, just press start, then press 'restart race' or 'quit'.
Edit: my prediction applies to road cars. I have no idea how they'll handle it in Nascar and rally, but I am hoping for something besides the standard "small delay, back to middle of track and righted" strategy.