Blizzard is very familiar with the advantages of cross-platform play, because Hearthstone exists and does quite well for it with exactly that. But there are other titles in Activision’s larger house able to benefit from cross-platform play including Destiny 2, the Call of Duty series, and the Skylanders franchise. But don’t expect it to happen immediately, as Activision representatives have stated that it would take some time to implement this in any of its games.
The publisher is quick to point out Hearthstone as an example where it works, but even if Sony’s current testing works out well, most of Activision’s stable is not currently set up for cross-platform antics, which would make changing that a significant undertaking even once it happens. Of course, Activision also hadn’t claimed that big mean Mr. Sony was the reason its games didn’t have cross-play, so that certainly eases the sting.