Axl is just playing it safe and releasing songs that were leaked... He has plenty of other stuff that we haven't heard that he may just be too afraid to release at this point, or figures business-wise, let's officially get out what's already out unofficially. Those leaks are from 1999, and we know he recorded vocals for at least Shackler's, Scraped and Sorry since those—so I think it's pretty naive to assume there's no other stuff out there. It may never see the light of day, or it may not be great, or a number of other things, but trust me, there's not just 3-4 more songs with vocals left.