FYI, arm can already handle most Open Source Software with no problem as far compiling them is concerned. In particular, Qt and GTK does work, and cross compiling too is very easy. Not that it's necessary anyway (aside of probably faster compilation unless you have really good ARM CPU). In particular, QEMU have qemu-user (if you didn't know), which basically Rosetta for Linux, but with a good performance hit when testing cross-compiled code.

Edit: In my opinion, what will switch the faster to a non-x86 on a large scale (for computers, not counting phones, tablet and microcontroller, not using them anyway) are servers. A lot of them use standard open source software, so switching might be pretty easy if the package manager abstract it (like... All of those I know).

I mean, certain cloud provider are starting to offer renting such servers (and not speaking of all those hacker who host server on raspi (and then those who use standard linux on mobile phone too))