I'm not knocking Mozilla for taking money from Google, it was a smart move. Most users would use Google anyway, so Mozilla pocketing billions by making users preferred search engine the default didn't really hurt anyone. Some of that money should however have gone into a trust or some type of investment so that funding for browser development would be safe if the ad money ever dried up.
Maybe someone at Mozilla knows something I don't, but there doesn't seem to be much planning for the future.