Honestly, the only thing that would have a significant and permanent effect on sales (in my opinion) would be addressing OMD somehow and bringing MJ back as a major character, even if not Peter's wife or romantic partner. The main problem for ASM right now, as I see it, is that the Spider-Man fan base is heavily fractured with a large number of people who simply won't buy Amazing Spider-Man out of principle, no matter how good or bad individual issues are. If a large enough number of those readers are brought back, I can definitely see ASM doing at least 70k consistently.