There's far more downside for Disney from anything like this that it makes no sense. Marvel and LucasFilm were cheap given the income they've generated and will generate.
Ehh, one could argue Disney would market the hell out of it and get more value out of it then Nintendo ever could, (mass merchandising,theme park, movies, TV shows, synergy ++ etc.)
But even then, it would only be good under the most ideal of situations.
The more realistic situations (if bought) would be:
A) Leave Nintendo at creative freedom and do little to touch the franchise besides some much needed marketing. (2nd Most likely given Marvel and Pixar... but Disney wouldn't get as much value as they put into the purchase.)
B)Disney gets totally involved in Nintendo and puts their IPs at maximum value and puts them to work on games for their various IPs. (Least likely... no precedent for this whatsoever... something that Ninty fans will fear.)
or
C) Disney integrates Nintendo like Star Wars by providing merchandising, marketing, rides, funding, more possibility of TV Shows / Movies... leaves most creative freedom to Nintendo. (Most likely given how Disney has treated Star Wars ... and inevitably Marvel.)
EVEN THEN, in near perfect/ideal conditions, there a lot of cons and it doesn't seem to make much business sense to Nintendo, and
especially Disney, and their overall ideology.
Also I'd like to reiterate that Polygon's article is completely pointless. It's a HYPOTHETICAL with NO BASIS that is then followed up to why such a thing would NEVER HAPPEN. And of course, Smash Day really needed a Nintendo "needs to be saved" article.