X86 on the reform is possible if there are System on Module available with the processor and all the required connectivity to make it work with the Reform mainboard. If that exists, then anybody is free to create a CPU adapter board which physically and electronically fits into the Reform mainboard. Then those interested in X86 do not need to wait for MNT to do the work. That said, I’m not aware of modern X86 SoMs that meet these requirements.
About performance: I used the reform with the imx8mq for over a year and it was fine as long as I wasn’t using websites with heavy javascript like youtube or twitch and friends. A bit more than six weeks ago I upgraded from imx8mq to a311d and I can now confidently say, that for my personal workload, the a311d provides what I need. Example: the testsuite of my main project which took more than 4.5 hours on my old intel laptop now runs in only a bit more than 4 hours so in that sense it’s even an upgrade in performance for me. 1080p@60 youtube and twitch work flawlessly with software decoding. Clearly, the RK3588 will be another massive performance boost but not one that I require but just a “nice to have”. As far as RAM goes, the only times that the 4 GB ram became a problem for me was when trying to compile C++ projects on all 6 cores. Doing so, even kills my 8 GB swap. So I’m just careful to compile suspicious projects with -j4 instead.
About proprietary x86 applications: I’m in the fortunate position that I do not need the usual x86-only suspects – except games. For those, I had a lot of success with box64. For example, according to the ingame-timer, I already played 10:46 hours Stardew Valley in multiplayer networked co-op on my reform. Gameplay does not differ in any perceivable way from playing the game on x86. Zero crashes.