I am going to venture what might be an unpopular opinion on this forum, but one that I think a lot of people who don't eat and breathe games might share: WotC should not tinker with the game too much.
Because so much of my play is with new players (teacher who runs new beginner campaigns all the time at my school), it is really valuable to me that the game remain consistent. I don't want to be teaching a new version of the game to different groups, and I want the kids to be able to leave my beginner campaigns and blend together to form their own campaigns. That is much easier if we are all working from a common denominator.
I think 3PP do a great job of offering variety on the 5e chassis, and I see my experienced players starting to gravitate towards some of them. There is also the option to play older editions, OSR, etc. But I want D&D to continue to work as the "vanilla" game. And I need DnDBeyond to keep functioning without the massive disruption that big changes to 5e would entail. It's a well-integrated ecosystem, and it works really well for what it is trying to do. I am very much in favour of OneD&D maintaining the status quo.