It should/would be pretty simple to sync your Steam library to your PSN account, without sharing much, if any other data. There are plenty of other things which do something similar. And linking Steam/PSN has been done.Just the nature of product vs services. I'm sure this will be discounted and doubt it will be full priced and if not, I'll assume a good sale will be hard shortly.
I think the big issue here is you'd have to synchronize your purchases across platforms. I'm not sure if Sony/Valve are willing to share that information with each other, plus any other technical issues that may arise. But individually on Steam/Playstation developers seem to give discounts to when upgrading to new versions. I know when the PS4 came out people who owned PS3 versions of some games could redeem the PS4 version for free. Or maybe that was Microsoft.
Lest we not forget that once upon a time----Valve proposed some version of Steam on PS3 (which was killed before it really even took a breath). and when you bought the PS3 version of Portal 2 ---- you did get the Steam version along with it. And that was facilitated by linking your accounts. it was supposed to have cross platform co-op play, as well. I....can't remember if that ever happened or not.
But you shouldn't mistake the above comments as me generally supporting the idea that we need to have everything sync up and we should only ever buy a title once. Because I don't really think that way.
With HZD, specifically: 3 years is not a risk proposition for a buyer. Its not a bait and switch or some sort of trick or otherwise an artificial way to boost console sales. Those sorts of tactics happen MUCH sooner than 3 years. 3 years is a whole lot of time for you to buy a console game and enjoy the heck out of it. 3 years is....a surprise. 3 years is a developer dipping their toes into a new market. 2.9 years ago, a first party Sony port to PC was a pipe dream.
We don't have any real statements yet, about what ideas are driving the existence of this port. But, it seems to me that Sony is doing some low risk testing of the PC waters. And I wouldn't be surprised if PC gamers respond well, with solid sales. And I wouldn't be surprised if Sony ends up doing more timely ports of upcoming games.