They'd have been killed by Raccoons and Hawks imo lol, that portal had been open for ages there was always a potential chance that they could have gotten through it at any point after episode 1 of the season but no-one thought to reinforce Eddie's Trailer in case of this scenario..
Did the whole Hive Mind thing apply to these Bat guys? When Eddie was killing them was that affecting Vecna like the Demodogs being killed in USSR supposedly did?
Seems weird to me cos from the flashback scene I got the impression 1's exploring had lead him to something unique and individual(the shadow particle thang), and then he took control of it and morphed it into a spider like thing perhaps eventually becoming as you say a part of Vecna himself, kinda like Liquid Snake inside Ocelot in MGS, but then why would there be other bits of it knocking about nearly 20 years later in USSR I wonder, then it never seemed to "break out" of being imprisoned when all the others did, unless I missed something here.EDIT:Jus realised one of the USSR dudes says it went inside the Dogs, what did it achieve by doing this?