Irrelevant? You think third party software publishers see them as irrelevant? If you do then honestly, let me just laugh directly at you. Because you'd be so naive that I couldn't help myself from laughing. The success of third party titles on PS4, whether or not they are available on the Switch, is why it will continue to get more third party titles. The PS4 is an ecosystem where there the audience has many different tastes and are not completely focused on one sole publisher. That is its huge advantage when it comes to third party software. When or if the Switch reaches that point, when large-scale projects such as Yokai Watch aren't abject sales failures, then there would at least a starting point to discuss whether or not the Switch will overtake the PS4 in terms of third party coverage.
That's the kind of circular logic that has made third party publishers lose ground in the Japanese market over the years.
1. Put games on PS.
2. Games sell better on PS than Nintendo because the games aren't even available on Nintendo.
3. Conclude to stay PS-exclusive based on the above.
4. Rinse and repeat.
The cherry on top is that Switch is supposed to prove itself when it's not even being given a chance to do so in most cases.
But that mindset is what makes the Japanese sales charts so much fun to follow. PS and Xbox get trounced and third parties tie their fates to those consoles, so Nintendo dominates Japan not just as a hardware manufacturer, but also as a software publisher.
Then again, the PS4 is approaching its end and supporting the PS5 is dangerous because the previous three PS consoles (PS3, PSV, PS4) all stumbled out of the gate. Quite a few third party publishers will be forced to reconsider their approach and do day and date launches of their games, so the circular logic can't be used forever.