Try bumping the interest check again. And/or send a quick PM to those who originally expressed their interest. If they say no and no one else joins in the next couple days then ya, it's probably dead. But don't give up on it too quick. From the first post of an interest check to the first IC, games can take two or three weeks to get off the ground sometimes. You have to keep at it. 

And sometimes people are just waiting to see if anyone else posts first before jumping in. Seeing other people interested helps others make their decision.