I won’t speak for the committee’s planned “templates”.
But what you are looking for will definitely be possible with our traits proposal that @certik is about to prototype in the LFortran compiler:
See Section 6.4 of this proposal for a simple Vectorexample, and also this thread for further illustration.
@certik and team are presently making excellent progress on implementing Fortran’s legacy polymorphism, in the framework of getting LFortran to beta status. Once they’re done with this, we can expect them to start implementation work on the new traits and generics facilities.
It will get done. We just need to be a bit patient.