We halve the rewards every four years. Why not automatically double (or some other multiplier) the block size at the same time? That way things scale up gradually.
I'm sure there are other possible compromise positions as well. Honestly, the two sides just need to sit down with an experienced conflict resolution expert, and come up with a deal.
They did that a long time ago, both sides (core and miners) then came up with the Honk Kong agreement. Basically it was something along the lines of, miners will use core if they release their scaling method before a certain date (can't remember when it was off the top of my head). Core then broke the agreement by not releasing it in time...