I don't think the ratio will be quite the same, because as you point out yourself Xbox screwed up majorly this gen and I think they've learned their lesson this time.
That being said I still I think the change will be minor, because Playstation is just a stronger brand everywhere in the world except possibly the US.
Currently the split is around 70-30. My honest guess for next gen is something like 62.5-37.5
- Switch - 27m
- PS5 - 15.5m
- Xbox Series - 10m