Looking at how many Pump.io instances and associated services are gone.
Looks like there are exactly two instances with open registration (Identi.ca is closed for registration).
Considering that this page began in 2017 with an effort to disperse E14N Pump instances among the community, it is really sad to see how badly that effort failed.
There are some P2P schemes in which there are servers to provide temporary storage, so that could be a partial answer. Or something using a DHT as temporary storage.
The true answer from my perspective is that this is a field for exploration and no one knows what may be ahead.
@geniusmusing @lxo This is important. #GNU #Jami used to only send when both parties were online simultaneously. If the parties in the conversation are in different timezones, that may not happen often.
Users reasonably want end-to-end encryption (E2EE), but still want some basic usability.
(The experience back in the GNU #Ring days was pretty bad. Even today, none of my contacts will reconsider it.)