I agree that it would have some impact, but I don't think the existence of the Xbox SKU had a significant negative impact on the PS version.
We're basically talking about people who own both PS4 and Xbox One and chose to buy the Xbox version over the PlayStation one (or had neither, but chose to buy an Xbox to play Monster Hunter rather than a PS4) and I can't imagine that there would be too many people who fall into that category (espeically on a worldwide basis).
Overall I don't think there's any need for concern for Capcom. They expect 9-10 million for the Rise (do you have the exact figure
yazenov
?) and it will easily do that across Switch and PC. I think it will beat their expectations by at least 1 million. Then they'll have Rise G out to make even more money and after that World 2 (plus I would imagine Rise 2 for the next gen Switch in 2027 or something).
Following a multiplatform strategy in investing in PlayStation, Xbox, Switch and PC is going to pay off really well for Capcom and I think a lot of other companies can learn from it.
Edit
The PC version already came out 7+ months later. I don't think an extra 5 months would have added an extra million