Switching brakes from mechanical to hydraulics. Disk rotor question Can I use the disk rotor from the current mechanical brake when I switch to hydraulic?
Yes this will be fine.

The only caveat I can think of is rotor thickness, if you look closely on a rotor or read the manual, you should be able to find the minimum thickness.

This is different for different manufacturers but shouldn't affect a hydraulic disc brake, they automatically adjust for pad and rotor wear and will happily clamp a pair of new pads together with no disc in between.

See this question about pad material. I wouldn't worry about that either.