Yup. Switch is only mid-life. It has been extremely successful, but will likely get a successor mid-way through the life of the PS5. Provided Nintendo keeps the hybrid factor, I think Switch 2 will be another home run. Series X will likely do better than the Xbox One. I've said it before, but PS4 largely did so well due to Microsoft and Nintendo's screw-ups.
PS5 should pass the PS1, but will likely not match the PS4 in sales.
I don't know how or where you are getting this from. As it stands, unless the cheapest PS5 you can buy is $499, and there isn't a PS5 price at $299 by 2023. There is absolutely no indication today to suggest that the PS5 will not at the very least Bush PS4 numbers.
And this sentiment about PS4doing so well because of Nintendo and MS, is baseless; at least with regards to Nintendo. The Switch, as successful as it has been has not in any way impacted the sales of the PS4. So why should it or a switch 2 affect the PS5?
And as for MS, I would agree that because of how similar the two platforms usually are (PS and Xbox) one usually does well at the expense of the other. But that doesn't even really apply this time around and its something even MS has alluded to. I don't understand how anyone expects the Xbox Series to do so well considering how easy MS is making for you to not even have to own one.
I actually predict the PS5 will sell around PS3 numbers 80-90 mil. For Xbox Series S/X I predict 40-50 mil.
Ok... so you predict the XSX/S to sell about the same amount as the XB1... and predict that the PS5 will sell 20M - 30M consoles less than the PS4.
Basically, you are predicting that coming off the PS console with the most momentum a PS console has had since the PS1 - PS2 and the PS2 - PS3, the PS5 (barring any $599 surprises) will do only as well as the PS3?