That is a fair statement, and I guess we don't know. I suspect a future contentious blocksize change should take care of the fee rewards at the tail end. We are

That is a fair statement, and I guess we don't know. I suspect a future contentious blocksize change should take care of the fee rewards at the tail end. We are currently about 6sat/byte ($0.40/std tx) for a low priority tx today. Satoshi himself said "I'm sure that in 20 years there will either be very large transaction volume or no volume." That being said, there are plenty of older protocols without financial incentives that operate as expected, like Tor.