The idea is that bitcoin is widely used with millions of transactions on each block, so those fees will be enough.
I don't see that happening. It's close to impossible to happen actually, especially if you look back at how we're working on ways to scale off-chain rather than on-chain.
In the long run, miners will also be scooping up the fees generated through Bitcoin's side chains that they merge mine, so if the activity on these side chains explodes due to all the garbage that runs on top of them, miners will automatically benefit from that. In other words, there is no real need to worry about miners or the security of the network.
And who knows, miners might want to provide liquidity to the Lightning Network as well to generate more fee income.
For that to happen, there would have to be a solution to the scalability issue for the network to accommodate that much transactions and keep it running at a productive pace.
Scalability is not an issue now.
Scalability problem is just a marketing strategy, to make fools invest in shitcoins such as nano and bch. There is no issue with scalability now.
It would be an audacious attempt, to make a prediction for over a hundred years from now. And would simply be just choosing figures.
There is really no audacity . It's planned to happen, that is how bitcoin was designed.
From bitcoin white paper, by Satoshi
The incentive can also be funded with transaction fees. If the output value of a transaction is
less than its input value, the difference is a transaction fee that is added to the incentive value of
the block containing the transaction. Once a predetermined number of coins have entered
circulation, the incentive can transition entirely to transaction fees and be completely inflation
free