Voted 'need more data'.
The implementation is FAR more important than the actual idea. While mods can fix bugs and such in an unbiased way, balancing a game is a bit trickier. You'd need to create a panel of top-tier players who are actually top-tier in both 1v1 and 2v2 with all five factions. That's just to get a good foundation going.
From there you need a "mission statement" that basically answers the following:
- How should each faction play when perfectly balanced?
- Is this balance for all players, or exclusively 'top-tier' players?
- How far from vanilla can we go?
This is exceedingly important for the community not to become insanely divided and ultimately disinterested in the project.
The first question is fairly self explanatory: How does each faction play once the mod is 'done'? Are infantry blobs something we actually want? Should factions stay similar to their current play-style? Should factions change to increase diversity?
The second question is very critical to get mass engagement from the player base. Simply put, the average player isn't all that great (I'm certainly not - best case I'm top 250 as 1v1 ost, 500+ with others). Do we account for that? Something that's balanced for a pro-tier player (ex. high micro cost) could be very imbalanced for the average player. But something balanced for the average player (CoH1's pios) can become broken in the hands of a pro (CoH1's pio spam). Who wins in this situation?
Lastly, how far from vanilla would this team be able to go? Small tweaks will probably work for the majority of things, but what happens when something becomes fundamentally broken? Would replacing brit emplacements entirely with their mobile counterparts be acceptable? Would transforming Ost into an elite-infantry "quality over quantity" faction be possible? What about reducing Rifle's "dual upgrades" to a single slot, thus removing their "jack of all trades" viability?
Then lastly you have the issue with promotion. This could be literally the greatest mod of all time, turning CoH2 into the single most balanced and perfected game of all time: but it doesn't matter if no one plays it. Without Relic's direct support, it would never become visible to the majority of the player base (main menu article thing?). Even then, you'd still be left with custom games, which while fun, just won't replace the ladder and matchmaking for some.
So yea, go for it, but there's no guarantee of success. It's been tried before, and it's failed before - mostly because of the above issues. But if it DOES work, it could be great.