... All the 2nd layer technology stuff like the lightning Network is only going to reduce fees drastically. ...
LN is not a perfect substitute for on-chain, so not all transactions will be done through LN.
Furthermore, increased adoption of Lightning Network will result in more on-chain transactions even if most transactions are off-chain because of the need to open and close channels. For example, if 10% of the world uses LN and opens/closes a channel once per year, that alone will generate 44 TPS, requiring (very roughly) 6 MB per block.
... Which means we will need even more transactions to pay as the block reward diminishes. ...
Again, the need for fees is determined entirely by the need for security (against a 51% attack). It is possible that the block reward will be more than enough to provide sufficient security even without a subsidy, but there is a real danger that it won't.
The issue is that security is not a major component in the price of a transaction. The primary factor is the size/weight, which is not related to its need for security. There needs to be a way to tie security to price. Some ways to increase the price of security might be to somehow make more valuable transactions bigger so that they cost more, or perhaps to include the value of transactions in determining the "longest" chain.