Then you are messing up with teching. What about mp? Do you scale that as well.
What do you do with VPs? It's not only economy. Its army scale. You have up to 6 more players than intended in the map and you only need 2 VP (in most maps) to win.
Well, you are messing with teching, but the idea is that the increased number of points on the map would minimize or even negate the lower income of points or caches. I don't think the maps are big enough or with enough strategic points for a change to resource income like I've suggested to work but it's certainly something to be considered in CoH 3.
I don't think VPs are an issue; there can still be three of them to fight over (five feels like a lot in Lorch Assault but the map is limited in effective size due to the castle). You just have more units fighting over the same quantity of VPs when comparing 1s and 4s but how exactly is this an issue?
It might be worthwhile for Relic to explore limiting population cap at higher player counts (and potentially increasing player count), creating a more team-based strategy game. It might be something similar to the Total War experiment with the 10v10 matches where each player gets three units to command.