I think that having a license that is both open source and that protects the creator's ability to earn money from his creation (thus paying for it's maintenance

I think that having a license that is both open source and that protects the creator's ability to earn money from his creation (thus paying for it's maintenance really) is a very good and important idea. Personally though I wouldn't go with the TimeBomb idea, I think that if I ever get the chance I'll decide on a single expected revenue stream (such as sass hosting) and provide an open source license for use except for that purpose.