Honestly Arm and Risc-V are under rated. Not all are libre compatible but there are a few that work well with exclusively free software and have much less power draw.
All even half-way relevant architectures but x86 and z/Architecture are RISC nowadays: ARM, Power, MIPS (The Chinese tried to revitalise it but they seem to be switching to RISC-V), Atmel AVR. Oh speaking of microcontrollers: Z80 (CISC) still lives though arguably it's genetically an x86. And then of course RISC-V which most of all is an open standard, and a clean slate. Also, the first vector insn set that also runs on hardware that isn't a supercomputer.
If you want to talk about underrated look into POWER CPUs.
Motherboards like the tallos 2 are completely open source( except for an nvme storage controller) and they already offer x86_64 levels of performance. The only con right now is software support and the cost.
Not only will ARM and Risc-V likely not save Linux it will most likely harm it. I doubt there will be many Linux computers running Arm and Risc-V and the few computers that use those architectures won't run Linux well. M series Apple computers only run with reverse engineering and even then many basic features don't work.
Most software doesn't work on arm and despite many distros supporting arm there aren't many arm computer manufacturers supporting Linux. There is a small possibility that Qualcomm could announce that their desktop CPUs support Linux but I'm not so sure.
Walk up to a random person and say "yeah recompile this software for a different architecture while having no support as the architecture is unsupported"
Yeah I could personally do that with minimal effort but keep in mind the vast majority of people aren't willing to. Most new Linux users get scared when they see a terminal, how are we supposed to convince people to give up tons of basic hardware features and tell them recompile software when they can keep using a proprietary operating system?
The proprietary video drivers for ARM SoCs have definitely been a problem for years and we can't rely on third party alternatives or first party support from linux popularity.
As far as software supporting arm, there are translation layers that can run x86 binaries on it and I am confident with more development and more powerful chipsets that won't be much of an issue for most applications.
That's the problem, right now arm development boards for Linux are limited which limits development of arm software on Linux which decreased the incentive to run Linux on an arm device. What computer manufacturer that uses arm processors that are comparable to standard Intel/AMD CPUs also supports Linux?
It's great for the price, but it's got plenty of issues.
The gpu is worse than useless most of the time, the cpu is perma throttled on Linux, split battery issues and you can't choose which one to use or when to stop discharging, the keyboard is worse than on the xx20 models, USBC can't be replaced
Also, you missed the point of the joke. T480 most certainly does have IME, and it can't be corebooted.