Switch's lead after these holidays is going to be frankly scary.
PS4's 4th year was it's peak correct, which Switch is running aligned with at the moment?
Yes, the PS4 peaked in its fourth year. Then it had another good year in its fifth year before it started to decline significantly.
We are already at the point where it's safe to say that Switch will have a good fifth year that will at the very least match the PS4's performance, so Switch will maintain or grow its LTD lead over the PS4. Afterwards Switch can afford to decline significantly and still beat the PS4 by a comfortable margin, because the PS4 doesn't have good years left.
But the way Nintendo has managed to hold off from price cuts and revisions through four years makes it much more likely that Switch will just keep growing its lead as time goes on.