In some games, this is still a very interesting area to explore, with lots of interesting choices even for the losing player, but in others (Risk, Go, etc) it would usually be better to stop and play something else. In these cases, bargaining over fractional resignations can work well.

For example, I might think I have an 80% chance of losing, and if further play doesn't seem fun I could offer my opponent 80% of a resignation. This is something that we would think of as essentially equivalent to them winning four games and me winning one game. If they think they actually have a 90% chance of winning we could bargain and maybe end up at 85%, but usually that isn't needed.

This does mean that more games end in resignations, but only in cases where that's what everyone wants. It works especially well if you're gaming with someone who doesn't like to resign if there's a chance, but you're playing games where finishing them off can be just really tedious.

In games with more than two players, negotiating fractional resignation should still be possible, but I don't think I've ever done it. It's more common for these games to have dynamics that keep it interesting for everyone, however, so this is often less needed.

(Avoiding the need for this usually looks like keeping the possibility of anyone winning relatively live until the very end, through some combination of randomness, secrecy, and last-shall-be-first dynamics. For example, when I play Modern Art we usually don't know who will win until we count up the score because people's amounts of money are too hard to keep track of, in Ticket to Ride you don't know what sort of progress opponents are making towards their tickets, and in Power Grid the "penalize the apparently leading player" dynamic is a strong equalizer.)