I assume RAM will also be a major constraint for on device ML; most Macs still default to 8GB (with absurd bumps in price to upgrade) so I'd guess some very high percentage of Macs sold in last 2 years are going to be quite bad for any major new software stuff Apple release in 2024. That is assuming they even are supported at all; if Apple follow their iPhone playbook they might just release the new stuff on late 2024 Macs.