This hasn’t been my experience with Diet Coke I’ve accidentally left in the freezer overnight. As long as I let it sit on the counter and thaw over the course of a few hours, it retains its carbonation, or at least some of it.
So long as you don't open the bottle before it has had time to redissolve the CO2 while being nice and cool you should be fine. Same thing applies to shaken or heated soda, so long as the CO2 doesn't leave the bottle it's reversible no problem.