I'd personally sooner end it than string it out for the sake of two or three posters like some other games, despite how excited I am/have been about some of my plans for Clark and Lex.
As someone who was interested in joining, reading through the IC, and jotting down a CS, it is rather disheartening to see the GM say this. It doesn't show confidence, and thus won't inspire others to post or join. After reading this I'm not sure if I still have a desire to join, as a game where the GM is talking about the potential end as soon as things hit a relative slow patch doesn't make for the best experience. I have ideas and concepts I would like to explore in this world, but not if the GM is already losing confidence in his own game.
Just the thoughts of a stranger who isn't officially a part of this.