My thoughts:
1) Simplify the law. The attackers front foot must be level or behind the last defender.
2) Var should only rule offside if it is clear and obvious.
I certainly realize "what is clear and obvious" is still subjective but it is one hell of a lot clearer that slowing it down, zooming in and watching it 5 times. If you watch it a couple of times and are not sure, check is over. Onside. No zooming in and watching it 5 times. Having to zoom in already rules out "obvious".