Reading between the lines, the govts and other authorities seem convinced this was a criminal act, so IMHO we can definitely expect some changes to the satellite tracking systems so they (a) transmit the position (i.e. the airlines will have to pay up the fairly trivial amounts involved) and (b) cannot be disabled from the cockpit or cabin.
None of that is technically hard. Maybe relocating some circuit breakers.
Every electrical system or circuit breaker removed from the control of the flight crew is an added fire risk.
Let's not be in such a rush to quick fixes for one in ten million risks that make more-likely risks worse.
If this pilot really did what many think he did, it was a clear "go out in style" job, which some may want to copy. Let's face it, it is amazingly easy to do. Either pilot can do it if the other leaves the cockpit.
I cling to the the perhaps naive view that there are not that many commercial pilots out there waiting to take out their aircraft and passengers - waiting only for suitable "inspiration".
If there is someone like that up-front who has decided that today is the day then basically we are pretty much stuffed. New tricks for finding the wreckage afterwards are not that much of a comfort.