Only as safe as the engine..
Post remap the turbo, engine or clutch could fail straight away... Bad times On the other hand you could have 100,000 miles of faultless fun ...... Happy days!!!
With remapping, chip tuning, hardware tuning, modding ect.. there is always an element of risk, if this risk worries you or could cause you financial hardship then keep the car 100% stock and dont tune.
IMHO I would say around 80% of the cars we tune are faultless, 10% minor issues, boost pipes popping off, coil pack failing, maf ect. then 5% more major with clutch slipping, oil pumps failing ect and 5% with turbos failing.
Is bungee jumping safe??? I would not do it just in case the elastic band snapped...lol