As it is now, a 3 or 4 player game in which one player has such a dominating lead that the outcome is not in question must be played out, unless one of the losing players is willing to take a draconian hit to his/her ranking and resign. If I was playing with friends with physical cards at my dining room table, the players who are behind could say, one to the other, "Shall we just quit and let him/her have it and start another one (or pack up)?" and if they agreed, either the group could start a new game or go home.
I'd suggest letting the player who is in second place propose resignation and if the player in last place agrees, the game ends with the same effect on rankings as if it had been played out with the leaving player winning, while if the player in last place does not, the game continues. Of course, bugging out for a rankings hit should still be an option. For the vanishingly rare 4 player game the player in second place would need agreement from those in third and fourth place.