The problem I see with this is if it was reduced to 10%-15% to win, then the small maps you would only need to capture 2-3 bases to win. If you just need to capture/destroy the HQ, then you might see a mass wave just fly straight to the HQ from the begining of the war to win it in under 5 minutes (bigger maps it would take longer). Maybe if we combine the two, like you have to capture 30% of the enemy bases and reduce strats and HQ below 20% to win.
I don't know, I'm just thinking out loud..