so it's entirely possible for Akai to pick anything they want... though at this point I'd suspect that they are familiar enough with ARM as a platform that they'd probably stick with it.
I just read the specs really quickly, and it wasn't apparent to me that the SOC that the SCB is based on is a drop in replacement, though it is possible. The MPC X/Live/One is based on Rockchip RK3288, and this is the RK3588. This has a comparison
https://gadgetversus.com/processor/rockchip-rk3588-vs-rockchip-rk3288/.
They both have the same ISA version, which would be a good sign for a drop in, potential for broad binary compatibility, but you need to remember that the MPC is made up of a lot more devices, and the OS layer probably cannot address (at least cleanly) a lot of the added features and functions. The biggest callout for this would certainly be changes in addressable memory and number of CPUs.
A few points, the single core speed for the new chip is a base 1.4ghz, which is likely kept lower to reduce thermals for running so many cores, and the older core runs at 1.8ghz, which may very well mean that the older chip could actually run faster, since they are both on the same ISA, if the RK3588 isn't able to run at 1.8ghz for long periods of time. I doubt this would be an issue, but I'm speculating that running all 8 cores would likely cause it to throttle lower. More compute power, but operating slower... and this can indeed cause problems in the audio domain for juggling buffers and such. Anyways... just a guess.
Max memory goes from 2gb to 32gb... which I am sure a lot of people would love, but this is likely cost prohibitive. Fortunately the memory bus speeds are much faster, which means that having more cores addressing the memory *shouldn't* be a bottle neck for large audio workloads.
Honestly though... the memory is probably the biggest upshot, and I doubt going from 4 cores to 8 cores would double the amount of CPU... sure it'd be nice, but are people going to be jumping to upgrade for *just* double CPU performance and more memory? The rest of the features called out like 8k video and stuff, hardly make sense unless they moved to having HDMI out in the first place... I guess I put it in the "nice to have" kind of upgrade space, but it doesn't look like something I think is massively compelling for them to move their product line to from a marketing standpoint.
anyway... enough techno babbling for now. I'm sure others that have more time could weigh in with better details.