[AgentME]

No, transaction volume and congestion is the thing that drives transaction fees up.

If transaction volume (and fees) stayed constant, then as the minting rate goes down, there will be a lower reward for blocks, and some miners will drop out of mining because it's not profitable for them. Miners dropping out will lower the mining difficulty, so the remaining miners will get a bigger cut. The system finds an equilibrium. Mining profitability only affects the mining difficulty and miners themselves (and the amount of resources necessary for a 51% attack, but as long as that remains obscenely high then the specifics don't really matter in this discussion).