I still think we're not on the same page.

Maybe I should have made it clearer, I'm speaking under the premise of replacing the battery cradle as well.
Whereas (I think) you are talking about simply buying a new battery pack, without replacing the cradle.
Here's what I think about the point you're making: (please correct me if I'm wrong)
- If current generation Hailong goes out of production, the next generation may not have the same battery cradle (base), so if you have a bike with the current generation Hailong casing, the next generation Hailong may not fit.
My point:
- It wouldn't matter if the next generation battery has different battery cradle, as long as the new battery cradle is made to fit the 2 water bottle holder holes.
- You would have to go through a mild inconvenience of replacing the last generation cradle to the new generation cradle (base).
I think what you were saying is, the new generation battery won't necessarily have the same cradle.
But what I'm saying is, you can simply replace the cradle, and what I meant by "universal" was that, most (if not many) bikes will have 2 holes for water bottle.
But my point was, if you get more proprietary pack, such as Bosch or Yamaha, you can just put these packs on any bike frame (even if they have the standard 2 water bottle holes).
Also, I can't say this for certain, but someone here on EBR said that Bosch has this communication system that their battery would only work on Bosch motor.
This applies to half-integrated battery packs, fully integrated battery packs, or any other proprietary or custom designed packs. Anything that you can't simply bolt-on to 2 standard water bottle holes.
Though, I do agree that at least for now, Reention Dorado (half-integrated) is pretty safe in terms of future-proofing, as they're very popular.
Bosch and Yamaha for example, I don't think they're attached on to 2 water bottle holes.
This is what I meant by less "universal" because you can't just go around and attach them on any bike.