According to Telegram's Pavel Durov, "A project of our size needs at least a few hundred million dollars per year to keep going." [0]. Telegram has close to 500 million monthly users, how will Signal pay for their operations when they approach the same numbers, which I assume is the goal? A business model will be needed, Telegram only recently started talking about how to bring in money from other sources than the personal savings of the founder.
Edit: Is it really relevant to compare to SSH? Does SSH have user signups or servers that handle large amounts of real time communication? How many developers does SSH have employed?