What’s next for the Steam Deck?

I don't particularly agree with this, though it's an argument very often used.

Pretty much all game engines moved to deferred rendering in the last 15 years. This was necessary as we now make heavy usage of real time sources of light. With that, effects such as fogs, transparencies, foliage, volumetric clouds, god rays, pretty much everything that previously would simply be an alpha layer are now heavily reliant on temporal reconstruction techniques.

The trouble is, if you ever used Unreal Engine's TAA without FSR or DLSS, is that it looks horrible. You can find threads and threads of people wondering why their games look like Vaseline smeared pictures, or why everytime a character moves there's horrendous ghosting, or why small details look like watercolor paintings.

FSR helps a bit, but DLSS pretty much gets rid of all these artifacts - it's temporal reconstruction that actually works effectively. So of course games will start to heavily rely on it for their rendering pipeline to look good, and for effects such as smoke to work well without tanking performance. DLSS isn't meant just as a performance saving technique for low to mid end hardware, it's a way of doing image reconstruction with better quality and performance simultaneously.

While we still can't render most games entirely using ray tracing, and instead rely on traditional rasterization with deferred rendering, DLSS (and hopefully future versions of FSR) become essential.