[user104658]

Originally Posted by Dia.

It sounds like Sony realised they were only harming themselves by not allowing crossplay, seeing that it could lead to an Xbox generation next time around

It's possible they've been intending to do it on PS5 for years, but the install base of the PS4 was already big enough for it not to be a consideration... so they've "sat on it" for as long as possible to mostly keep it out of the PS4 generation, but are releasing the info now that next gen hype / advertising will be starting to ramp up.

Also possible (unless they had inside info) that Xbox was planning to use crossplay as an advertising weapon and now will be scrabbling for a new hook .