They've been going for 3 months now and are still going strong. Yes, older members don't provide additional revenue from entrance fees, but SBI puts out weekly updates and a few other posts that it encourages members to upvote. If you upvote consistently, you can get more shares. The upvote money can be used to help fund the project. Also, some members don't post every day, so don't pull from the VP. Other members go inactive and aren't posting at all.

Good questions!