Can't we just hope that it's at least HL MM they are making and not AR?

Assuming we get HL with no whitelist and said OP weapons turns out to still be OP.
This will only show valve that the weapons are actually too good and they will be nerfed properly everywhere. Thus, we will no longer need a whitelist.

It might seem un-appealing at first glance but I think this could turn out being a win for everyone in the long run.

I seriously doubt that they're focusing on Arena:Respawn due to the fact that we've already seen signs pointing to Highlander and the fact that it doesn't seem like the Arena:Respawn devs have been approached by Valve about such a possibility. Arena:Respawn is a mode still very much in development, and it would be surprising if Valve pushed their competitive matchmaking with an as-of-yet-unfinalized game mode which has yet to see league adoption.

its gonna be player skill rating for MvM and they're gonna improve the lobby system for it and thats all this update is gonna be.

^rofl if true

As I've stated before, the exposed code confirms that this new matchmaking mode and MvM are mutually exclusive, so it's definitely not that.

all I do is repeatedly queue for the same 3 missions and never complete a tour, because I don't wanna pay but I want teammates that are paying so they're not idiots. this would actually be awesome for me.