I think you vastly overestimate how much the average consumer thinks about or cares about OS updates.

What you say is something that could affect the decision making process for highly technical people, but even then... we have no firm commitments from Apple on which platforms will get the longest support, so it's a gut-feeling decision, which isn't very technical.

As you hint, the M1 could be treated as a pathfinder platform and deprecated much sooner than subsequent platforms, kind of like the original iPad.

The M1 is not ARMv9 and lacks SVE2... ARMv9 is coming soon, and that may become the long-term supported standard for Apple's Mac-on-ARM platform.