It's a really cool idea that depends largely on if people are musicians and if you have means to record and post things. I'm sure you could get it to work with some creative ideas, but I think it's a bit of an uphill battle. I've seen people attempt to do RPs where all the participants would draw little comics for each of their posts, and it was REALLY cool to see unfold, but they don't typically last long because if you think getting writer's block is bad, try adding the pressure of drawing a comic with every panel to it. 

I hope you get this idea off the ground!