If you think a fork is hard to achieve now, just wait until 2020...
I'm not saying it's gonna be easy, but the fork only looks hard, because the solution looks too simple.
I can explain, why anything less than 8Mb is not competitive enough to justify the fork, anything more than that is risky for network's health.
If we just get used to the idea, that we need to come together once in a while to make adjustments it will be healthy for the community.