I started this generation with a Series X, and plan to pick up a PS5 at some point. I do not think that will happen until at least next year. I simply can't justify the purchase at this time, as I already have a current gen system, and I don't have enough gaming time to make good use of both the series X and a PS5 at this point. 

I definitely do want to play Horizon Forbidden West though. So, I need to decide whether to play it soon on my PS4 Pro, or wait a year or two until I have a PS5. I'm curious to see what others think I should do.

Let me know what you think.

And just to get this out of the way, it is highly unlikely that I will play the game on PC regardless of when it launches on that platform. I've been gaming on console for 40 years, and that's where I play essentially any game that is available for consoles. No plans to change that in the near future.

It depends on how badly you want to play the game. Do you care about all of the bells and whistles? Or do you want to experience the game at it's best on PS5? Honestly I don't know what to tell you. It's clearly your preference.

I didn't experience Zero Dawn until I had a PS5 (that's how much back log I had), and I was not disappointed with the newly patched 60fps and such. Then again, I'm more than sure that I would have loved the game even without it.

Play it now on ps4 pro and play again on ps5. It's free upgrade so you don't need to worry about buying another copy for ps5

Why not sell the PS4 Pro? You get good prices for it.

I sold mine for €300 a few weeks ago.. the over five year old launch model with only 1 DualShock4.
The upgrade from PS4 Pro to PS5 (Disc model) costed me less than €200 and included a much better controller and a fresh warranty.

Horizon: Forbidden West and many of your PS4 games will profit from the performance upgrade... 60 fps instead of 30 fps is a game changer!

I doubt that you save money by waiting another year for buying the PS5. Prices for used PS4 Pros will plummet until then, but the PS5 probably won't get a price cut until then.

Yeah, but I'll still have to work to get my hands on the PS5.  I just don't have the desire to deal with that right now.  

You do raise a good point about selling the PS4 Pro now though.  I could do that, just go without any PS system until I happen across a PS5.  

I would say start on PS4 pro and end on PS5 so you get treated to really good visuals twice. The higher res textures, more polygon dense environments and either 60 FPS or a higher res and extra fidelity, surely will feel like a nice upgrade.

I wish I waited until I got a Switch to play BOTW. :(

Don't make my mistake.

Would play it right now, seems like good enough on PS4 base and better on Pro. And next year you can do a NG+ on PS5

I would wait if your plan is to play at the best possible quality. Though if you want the game so bad, go for it.