Offline messaging is important for a lot of people. Previously, my hope was with multidevice support, if you could have on device online, it could hold/route messages for the rest of your devices. Doesn't really solve all the problems, but it's an easy way to get closer. Anonymity and reliability isn't the problem. The issue we've always been blocked by was abuse. How do you prevent someone from DoS'ing the whole network. Evicting valid messages, or exhausting space for new ones.