At ~all times for a long period of time during Gitmos operation, there was at least one (revolving) prisoner that no nation on earth would take. I think that was the biggest challenge for someone who actually wanted to close gitmo, to close it. Not clear where you would put them that wouldn't be yet another prison.
I guess now that the US has normalized relations with the Taliban, maybe they'll end up sending them to them, not sure who else will take the last ones.
If we didn’t want them then why did we capture them?
A lot of them were captured for things like simply having an F91W watch and also being proximal or familial to a terrorist. They were initially wanted but then once 'cleared' the problem became once accused as a terrorist no country on earth wanted to take them even if they were cleared as likely innocent.
Obviously it was also politically infeasible to admit them into the general US.