ARM devices have become associated with App Stores, touchscreens, locked-down and dumbed-down systems. And there's a very real risk that Apple will take this as the opportunity to completely lock out any software that's not been censored and taxed by their App Store.
I personally doubt they will do that. If anything I could see them making iPadOS more capable, moving more of the consumer market there, and making the Mac line even more suited to pro users with more compute power and more OS capability.
BTW the ARM move could fit into this. I wonder how a 32 or 64 core A series ARM64 chip in a laptop form factor would perform? Our company runs some infrastructure stuff on Cavium ThunderX chips with 96 ARM cores and the performance is comparable to high end Xeons for very parallelizable load. The Apple A series core is far superior. I'd take 64 of those in a laptop.
It would be so fast I'm sure it would have no issue running transpiled X64 code at perfectly adequate speeds. Could probably even run X64 VMs in emulation at speeds that were at least quite usable for testing and dev.