Most drifters can't afford specialised drift tyres, so they do just use old (or new if they can afford it/are sponsored) street tyres. Remember: drifting started with guys on the streets.
And dirt drops are not uncommon, dropping a rear tyre (on purpose or accidentally) off the track. Though it usually happens when the surface next to the track is just dirt or grass, not the sand traps.
And what happens if another car is the cause of you flipping over? (ie an AI or online racer bumps you into a wall, and you end up on your roof). If your race is over because of that, it is going to be very frustrating, especially in a long or difficult race. And I don't think PD would like their players to not have fun while playing. So instead of simply "respawning", I would love for some track marshals to appear from somewhere and roll your car over when the coast is clear, maybe even under safety car conditions.
Another possibility is that the car will be programmed to always land on its wheels, which seems unrealistic so probably won't happen.
Anyway, that's just my thoughts