I think fees will work fine to keep miners in business, but that may be what happens anyway. It remains to be seen if the current granularity is sufficient in the long term to settle l2 and l3. But we can always add a couple of decimal places when the time comes, and that may extend the halving for a time.
I think we are still early and adoption will grow, especially when debt based fiat ponzi grows thus fucking the lives and financial freedom of the masses, more people will start opening their eyes for Bitcoin Freedom Money (they are doing it for gold but gold lacks the digital features of Bitcoin), as well as more businesses which will lead to more Bitcoin monetary transactions both on L1 and L2s and more revenue for miners from transactions. More value for everyone. Its the monetary transactions that transfer value. And its then when the Bitcoin blocks will be full. For now there is no need for them to be filled with waste spam. The block rewards are reasonable.
