I don’t see any way that the show can resolve the Dathraki and the Unsullied other than the following:
Everyone witnessed Daenerys tear apart Kings Landing. It’ll be hard for anyone, except her diehard followers.
Varys sent out notes before he died. I think it’s a good guess he spread the word far and wide about Jon being the rightful heir to the Iron Throne.
All of those groups will gather at Kings Landing, witnessing the aftermath of what happened.
Daenerys still wants the Iron Throne, and now her back is up against the wall. The only way to keep it is to object to Jon being the rightful heir.
I think she plans on killing Jon, and she’s going to try. By dragon fire.
But I think if that happens, Jon will walk away from it unscathed, proving he’s the rightful heir.
We’ll see.
GOT Finale in ten minutes!