Resumption is an option. However, in strict application of the rules, if it is found that the outcome of the game would hinge on who gets to play next, the game should be declared as “both players lose”.
If that’s not the case, and neither player wishes to resume, they could still attempt to score the game. I think that unclosed borders simply nullify territory (and prevent the removal or otherwise dead stones that resided in “non-territory”).
It gets a bit weird with unsettled positions. It can be the case that somethings are judged as mutually dead (this is informally called as “anti-seki”), but these dead stones are actually not removed for scoring purposes.