>>268063003
That would be nice but the cosmos adapters aren't even out yet, I belive the LH faceplate is slated for "Early 2020" and the wireless adapter is still "coming soon". Not to mention if you buy it now you can only play a few games with the inside out tracking because htc fucked up with game support. Your hands get stuck on the floor in pavlov and superhot, and some games can't even launch because of an error saying this game doesn't support the cosmos. 
I really want the cosmos to succeed but the software and hardware is just not worth the asking price. If you want steam vr for below $1000 just go for a gen 1 vive with the audio strap. 
>>268062110
Rift S, Quest and Index are all currently being supported. I'm not so sure about the regular vive but its still on sale and accessories are still being made for it. Cv1 is phased out, the only hope is if a company starts making third party cables. The other headsets besides the cosmos as stated above aren't really worth looking at.