I have a suggestion for the relay nodes
Could there be reward rewards monthly, yearly handled by community to judge and grant rewards.
To support relay nodes based on their best uptime they get rewards accordingly and community governance can give that from their threshold which there is some currently left now plus future donations which would make the threshold of algorand bigger with time.
This way the right reward serves the node operators
I think that the relay nodes should be rewarded on the hourly basis according to the liveness stats… Not just the relay nodes, but also the participation nodes, the indexer nodes, and the kmd nodes… If there would be pool of money allocated for them for each hour, it might be even called mining 
But in reality by the decision of the pool of distribution money there would be certain number of live nodes, and it would be the most economical to keep the most efficient running.