Understand that PS4 is and has been doing very well. Switch sales don't appear to have had an effect on its sales, and likewise the PS4 is not appearing to affect Switch sales. At this point in time, Switch is still supply constrained.
That said, even if Switch supply was able to satisfy demand, I'm sure the big third party games would help sell a bit more. However, Nintendo has for more than 20 years now been able to sell systems based almost entirely on its own games output.