When Apple announced the M3 processor they primarily compared it to the M1, there were also some comparisons to the M2 but it was clear that Apple was primarily focused on advertising the relative performance to the M1.

If Apple announces an M4 MacBook will it similarly be primarily compared to the M1?

This market resolves upon the first announcement at an Apple event, and is not dependent on comparisons after that event.

If Apple releases a different line of processors to replace the M series or if it is widely believed that there will never be an M4 MacBook this market will resolve NA.