Any regard given to the idea of consumable metal? Whoa, whoa, (ducks rotten tomatoes) . Hear me out. This fits the "Flavor" of the PA narrative, that these coms are destroying and consuming entire planets to fuel their petty squabbles. We can destroy them by crashing them into eachother, but can we not also destroy the planets by sucking the very metal out of them? My implementation would be after an extremely large amount of metal is extracted from a node, it collapses and is replaced by a deep sinkhole. Planets that have been heavily mined will thus be riddled with sinkholes, a telling reminder of the ravaging of worlds made by the commanders. This also would force expansion to new planets to maintain economic growth, and add pressure to keep expanding, and keep despoiling worlds. I imagine korean starcraft-like eSports games where players manage huge armies across many planets, some ravaged but still strategically vital due to their role in the infrastructure, like a Coruscant, and others wild and contested for their resources.
I'm not sure if I like a situation where you both have gradually less resources. You narrow the playing field and make the lategame succumb to even slower gameplay, where neither of the players have enough numbers to do anything. Let's say you're behind the other player, you will stay behind if there's just nowhere you can expand to. Let's say you're ahead of the other player, then destroying mass points can potentially hurt your own economy in the long run. I'm under the impression that the game will feature enough land deformation to deny mass points. I don't think we need a specialised unit for that purpose.
There wouldn't be a unit that destroys resource per se, as you said, Annihilation will cause planet destruction & land deformation, which will reduce resources. Instead I am saying that metal nodes would collapse after so much metal had been pulled out of them. As you said it does slow the end game down- if players are unable to continue expanding. However despite there being consumable resources in Starcraft, I never once saw a pro game end in a stalemate due to that reason. If anything it prevents stalemates.
We've been over it before, and for me at least it's too much of a departure from what sets the TA/SupCom/FA/PA Economy apart from every other RTS out there pretty much. Mike