The only games that I think are still worth buying the console for at this point is Pikmin 3, Xenoblade Chronicles X and "maybe" Paper Mario depending on how I feel about it when I play it.
I am contemplating buying a Wii U for these exact games, and these only! I will get one, just to round out my Nintendo home console collection (I was broke when it came out), but it is getting harder to justify. The only thing keeping me from grabbing one on the way home today is the notion that the ports of these will come to Switch. If they do, then there is no hurry. I can wait a few years and grab one from a flea market or craigslist for peanuts.
In terms of Ports hindering development of new games, this isn't the case. Logically it seems like it would, but the original dev teams aren't the ones working on "ports". These cheap outsourced ports are what fund massive AAA games. Big games are fewer and father between, so offering new adoptees opportunities to enjoy old games for the first time, and giving die hard fans opportunities to enjoy them again (at full retail price), bank rolls big expensive games. This is especially true of games from the Wii U, which probably barely recouped their development costs, let alone funded the next big game.
I'm torn, but excited. A good port example would be the precedent set by The World Ends With You. There are TONS of DS and 3DS games that I would love to have on Switch/big screen.