I imagine infinite scrolling would be much easier on the server (and overall less janky with less repeated posts) and therefore more likely to be added after 0.19.x due to the switch to cursor-based pagination. That said Lemmy devs may or may not be against something like that on the default frontend due to well being reasons (unsure on where they stand on this tbf)
That said, custom frontends do exist and I assume there has to be at least one out there that already supports it (and isn’t mobile only)