The crux of the issue is that miners incentives are not aligned with the network's users.
Both parties need a secure network. If miners raise fees enough (raising fees is in their interests already) to get to a baseline level of security, would users walk away? I don't think they would.
Do miners really need to be coerced into charging an adequate fee by a block limit? I don't think they do.
Miners need to be coerced into limiting the load exercised on nodes who are not rewarded for their work.
Remember that our objective is not only to optimize the miners' revenue model but to do so while recognizing the impact this has on the security model of the network.
I really don't understand what you're saying. What do the non mining modes have to do with this?