Fortunately, it appears that Sony may be willing to cave in slightly when it comes to cross-play with the world's most popular game. Shawn Layden, who serves as President and CEO of Sony Interactive Entertainment America, provided the following statement to Eurogamer on cross-play:
We're hearing it. We're looking at a lot of the possibilities. You can imagine that the circumstances around that affect a lot more than just one game. I'm confident we'll get to a solution which will be understood and accepted by our gaming community, while at the same time supporting our business.
At the very least, this statement seems to suggest that Sony will back off from the practice of holding Epic Games accounts hostage if you have previously played Fortnite on the PlayStation 4. As it currently stands, gamers that have already tied their Epic Games account to a PlayStation 4 cannot access their in-game purchases of progression on other consoles (Sony imposes no such limitations between the PlayStation 4 and the PC, macOS or iOS). Sony should really have no say over that you do with your Epic Games account, so backing off on this policy of blocking cross-progression would be greatly appreciated.
What's unclear is if Sony will enable true cross-play between the PlayStation 4 and other consoles. Given the statement about "supporting our business", that seems highly unlikely (even though it is technically possible). Also consider the company first and only other statement on Fortnite cross-play:
We're always open to hearing what the PlayStation community is interested in to enhance their gaming experience. With more than 80 million monthly active users on PlayStation Network, we've built a huge community of gamers who can play together on Fortnite and all online titles. We also offer Fortnite cross-play support with PC, Mac, iOS, and Android devices, expanding the opportunity for Fortnite fans on PS4 to play with even more gamers on other platforms.
Sony could surprise us all and allow cross-progression and cross-play, but we're not going to hold our breaths waiting for that to happen.
In the meantime, Microsoft and Nintendo are talking up the ability for Xbox One and Switch gamers to play Minecraft in cross-play, seemingly kicking dirt in Sony's eyes.