gas fees will not get affected by the merge from a users point of perspective (there is a lot going on for validators etc). This was not part of the plan.
In this regard there was kind of a shift over the last years of how Ethereum is working and wants to work. The current vision of Ethereum is roughly: There is a protocol layer (1) and an application layer (2). User transactions should be dealed with on layer 2 with fees around 0.1$. Layer 1 is considered as the generalized security layer to make specialized layer 2 possible without downsides. User transactions can be that cheap because they are part of an accumulated so called rollup, there are different kind of rollups for more specialized use-cases.
But to come back to your initial question. There are also updates in the pipeline for ethereum to increase its performance in regard of gas fees and ts/s >100x in the coming ~5y. There will be several small updates, way way easier to implement than the merge. The first should hit mainnet 2023.. but time will tell ;)
