I’ll have to disagree on the “It’s a handheld first” part, as I think Nintendo did its best to make it a true hybrid. Where you can see they accomplished is how people use it differently. Personally, I barely use it as a handheld and some games just need the big screen. But others play it bi-directional and some even mostly handheld. That’s the genius of the Switch … well, some of it. But the price was lower, yes.
Regardless, since they can’t compete with the two (actually 3 since PC gaming keeps getting bigger) powerbeasts, the Switch is a perfect place for unique games. They already have plenty, but if third parties are smart, and some like Capcom seem to be, more exclusive games should go their way with the occasional port. Astral Chain and Octopath each sold more than a million copies. Nintendo makes great games, but they can’t express enough of them on their own, so third parties should look at sales now! It’s time 
Nintendo should work with third parties for the Pro in my opinion. That way, not only will MP4 and BOTW2 make good use of it, but some third-party games can be part of the launch. And it would still be in the Switch family and continue to sell for several more years until it’s the successor.
It’s about providing new gameplay experiences for all Switch owners.
These can also mean add-ons, which can be tricky. The PSVR worked for Sony, but the Kinekt for MS … Not that much. But hey! It’s Nintendo. They like to surprise us.