Don't forget that more powerful devices, more battery and more energy hungry these devices are.
The arrival of x86 would solve all problems in terms of software, as everything can be run on it. The only emulator I recall that doesn't match windows is DS's Drastic, in terms of efficiency (desmume seems to require a lot of resources and some games are not 100%). But along with all the power that comes with it, so does the energy demand, almost matching Laptops. These can run a lot of software, but on batteries, just a few hours.
Unless they research towards power efficiency, we'll need to carry a laptop "sort of" power supply thing everywhere.
If someone wants to correct me if I'm wrong, go ahead
this is a subject that I've thought about recently. It makes sense, no?