Maybe but we won't get another iteration of the cross battles that's part of the reason why Adam left in the first place because I'm pretty his entire team was eliminated in the cross battles but idk
According to the voice Wikipedia page not the fan one the actual one Snoop is in chair 1 gwen in chair 2 Michael in chair 3 and Reba in chair 4 but I could see that changing between now and the summer
Ya if Adam didn't back out for s17 we wouldn't have seen gwen on that season however I do think we see her in 19 and we get Adam's exit after season 17