Will they be the first?
While it hasn’t happened yet, Blizzard might be blazing a trail for a major console development. According to the official OverwatchTwitter account, the publisher noted that they will “keep an eye on cross-platform possibility on consoles.” While they’ve confirmed that PC cross-play will definitely not happen (because both platforms are balanced independently, and mouse and keyboard players would have too much of an advantage), they’ve always been open to connecting both consoles.
This isn’t as crazy as it sounds. Just recently Microsoft opened the gates for cross-play between other platforms, including PC and other consoles. With that bell rung, Sony has the chance to extend a hand and allow the PS4 to play nice with Xbox One, at the behest of the developer. While Blizzard is open to the idea, “keeping an eye on” the situation likely means that they have no say in the matter, and will need both publishers to come an an agreement.
An agreement that Sony probably won’t want to make, as they’re the market leader by quite a bit.