A fee market will be needed at some point, even tho its not necessary now.
Also, dynamically adjusting block size, is almost like having no block size limit. It can be gamed, and will increase with the effect of driving fees to zero.
edit: unless another way can be found of paying miners, such as discarding 21 million limit and having a small constant reward.
(also unlimited block size might lead to huge blocks and problems for network)
I often read that people believe that without a block size limit we would not have high fees. But we clearly saw in the past that this is not correct. The blocks were not full all the time, not even meeting soft limit often. And still people pay a good fee. It's not that bitcoiners are a bunch of cheapskates.
Then let's double the amount of transactions by rising adoption of bitcoin and you have a solution that works.
I don't see an artificial limit needed. There is already proof from past experiences.
How much was paid in fees in the past? It was not enough to pay for securing the network if mining reward were to become negligible.
The fees were statically set, to such a small amount that most people simply could not be bothered to turn it off and were happy to donate the tiny amount.
Bitcoins security is based on proof of work, and that can not be sustained by donations. It was NEVER sustained by donations. It is and was sustained by coinbase mining reward, thats why it can function without a block size limit now.
An economic incentive will be needed in the future, and that can only come about if block size is limited.
The thing is that satoshi wanted bitcoin to replace fiat to get people out of the hands of the banks. You can't do this with high fees.
And he created the fee system and the block halving. He said that the fees will replace the block reward step by step. And it will. But miners can't await that the bitcoin network can survive when they await that we raise the fee with each block halving. It would be instant death to bitcoin.
Saying that... it means that miners will inevitable earn less. UNTIL adoption comes into game. The more transactions the more fee. That was always the plan. And we will kill that plan when we start to think like "Miners don't earn enough, we need to raise fees." It should not matter what miners want since of course they are in it for earning money. When half of the miners drop dead because they can't be run profitable anymore then be it. Be insured that the rewards will still be way enough to secure the network. But we can't feed all miners without end. That won't work.
Unfortunately miners are the one who decide the development of bitcoin nowadays. And that might mean higher fees will come. Raising the fees with an artificial limit is somewhat unliberal. It's like a bank consortium deciding on how high the fees has to be in order to run lucrative miners. It should not work that way. Miners has to be switched off. That happened all the time. And it has to happen in the future. Imagine all the old miners still working having them held lucrative artificially... bitcoin would be dead long ago.
The question is... will greed kill bitcoin adoption or will the far outlook win and adoption will bring the fees needed in the future?
But the bitcoin network will always be secure. You should not fear that.