The question was never improbability but is it worth it for the developers/publishers?

Let's see Bulk Slash running on a Saturn emulator running smoothly and little imput lag on Switch.

We're more than halfway through Switch's 5th year at this point, I think if these kind of "impossible" ports like World War Z weren't worth it, they would've stopped a long time ago.

I mean, yeah it's true.
But there are probably going to be some PS5/Series X games that would only be able to run 240p 30fps (or less) with awful textures and screen tearing.

Yeah I don't expect we'll see any PS5/Xbox Series games ported to Switch, as at that point it's kinda like trying to port a PS4/Xbone game to the Vita.

Just about anything on PS4/Xbone should be possible though, excluding of course stuff that's off limits for other reasons like first party Sony games.

The funny thing about post like these is that neither Sony or Micro are even making exclusives for them. So when exactly are these Ps5 or Xbox series even coming? By the time those plats have sold enough to warrant next gen only, Switch's successor will be on the way anyways. Also the Switch doesn't need titles from them to sell well.

Actually, none of those are PORTS. More like remakes using entirely different engines and assets to better fit the hardware. Pretty much everything coming to Switch has actually been ports with minor tweaks.

I believe the CoD games on Wii were actually running the same engines as the PS360, so those were ports. Meanwhile something like Dead Rising was rebuilt using the RE4 engine, so its not a port.

Are developers going to essentially remake games or create a different version to better fit the Switch? I doubt it, it won't be common at least.

Ratchet & Clank: Rift Apart and Returnal.

The main thing you need for a competent Switch port is a dev team with the right combination of hard work and talent.  Saber clearly has that.  In fact, I even suspect that hard work is even more important than talent in these situations.  A lot of these Switch "bad ports" are really "lazy ports".

The other factor is that we are now at a point in video game history where adding a ton of raw power doesn't give a whole lot more in effective output.  It improves graphical capability somewhat, but that is about it.  It used to be that new hardware would also enable new and better gameplay and not just better graphics.  I don't think Street Fighter 2 could have been ported to the NES without major sacrifices in gameplay, but it runs great on 16-bit consoles.  I don't think open world games like GTA3 or Shenmue would have worked on the PS1, but they work great on Generation 6 systems.  I even think the giant boss fights in Dark Souls wouldn't work in an earlier generation, because on the PS2 the best we got was Shadow of the Colossus (and those are really not the same thing, gameplay wise).

However, I haven't seen any games yet that have gameplay that wouldn't work on the Switch.  Maybe VR games? (But those aren't really popular yet.)  As far as non-VR games, the Switch can play all of them without sacrificing gameplay.