The M3 can be partially fixed as you can turn off DMP on the M3 not the M1 or M2 and doing that seriously degrades the performance of the processor, M1 and M2 are cannot be patched at all. I'm not up for buying a chip that has two security flaws, the M1 and M2 had another flaw already that could not be patched. Intel chips have that vulnerability too but like the M3 can be patched.
Apple's M-series have two types of cores: big Firestorm cores and little Icestorm cores. The DMP-based GoFetch exploit only works on Firestorm cores it appears, including M1 and M2 CPUs. The GoFetch paper suggests all cryptographic work should solely be run on the Icestorm cores for the time being. Running anything on the efficiency-focused Icestorm cores is bound to be slower, but it should hopefully be be secure.
I have no idea if Apple will implement this with the next update but I will move away from the from the M2 Pro when the M4 lands with a pro variant probably on the Mac mini. My worry is Apple want people to update computers like iPhones and that really should not be happening. Also this push for AI concerns me because macOS will loose some new functionality unless you have a M4 depending what Apple have up thier sleeve, and for people that have just got a M3 thats a low punch.