I don't think postponing the game until we find a sub is a good option.
The game is already hanging by a thread. What with two players missing and the TC AI running amok. Add to that an indefinite wait for a sub and you may cause the rest of the players (me included) to lose whatever shred of interest they had left in this game.
Hey, if you so care for R'lyeh you should arrange some incentive for the potential sub, like a free supply of blood beer

made in Mictlan breweries
