If we put aside Killer APPS (including Safecoin)… the SAFE Network must achieve 3 things for mass adoption.
1.Strong Data Security. I think we have this one locked down with self encryption.
2. Fast Data Delivery. Still working on more efficient routing. This one needs improvement regarding large files.
3. Competitive Storage Costs. Safecoin rewards attract more farmers. Abundant storage increases PUTS per coin. See this post for a detailed discussion on storage costs.
Killer APPS help the Network economy. They encourage more PUTS/GETS which cause more recycling/farming attempts.
TL;DR, I think Safecoin has the “potential” to be greater than any alt coin out there.