Do you think that doing into the future that, should these continue. 

The ones announced for Rocket League got some real shade thrown at them from other console ecosystems and the PC in particular, and I have to wonder how bad it could get with late game ports

For example....let's say that Injustice 2 was to port itself to the Switch at some point next year, and as a incentive to buy it alternate skins based on Nintendo characters pops up on the game. Perhaps Black Canary in a Samus Zero suit, or Green Arrow in a Link (BOTW) champions tunic. 

Or for a more likely nasty set, Overwatch. Should the mythical port occur, and Overwatch characters are given Nintendo skins (Perhaps Reindheart as King Dedede, Tracer loke Fox, or Widowmaker in a Zero Suit) that are exclusive to the Switch......how much fury would that generate?

So, how will this work with cross-play? Will you be able to see the Nintendo-exclusive skins on the Xbox One?

The way I see it, is if the game is to have unique platform skins for each system, then those skins have to be equal in number. Each console version can be backed by their respective company for skins of their own, but PC doesn't have a company to do that, so it's up to the devs to do so and well, if they don't then I can see why that side would be pissed.

I don't mind the skins, so long as each side has their own unique ones and not only one side alone.

Was there rage? Over Nintendo-specific skins in a game on a Nintendo platform?

Oh yes. See the Tumblr and Youtube comments after they got revealed. 

Color me surprised. 

I'm unsure why anyone outside the Nintendo ecosystem would expect them, or even want them.

lol seriously?

People need to grow up and get over it. Nintendo-related consoles are just a fun addition to Switch versions of games that don't impact gameplay.

My lord people are just ridiculous.

Do you have any source for that "outrage" at Nintendo? Platform specific skins or characters are nothing new for Nintendo or any other console for that matter. RL in particular did the exact same for PS4 and X1, so I doubt there was much protest that Nintendo also got their own cars.

I don´t think it would generate any fury at all, as they´re basically just skins, just cosmetic options

Exactly, I'm not getting this.  Tekken Tag Tournament 2 got exclusive stuff because Nintendo allowed/wished it.  If both IP holders are cool with it, players of other versions just miss out.  Like, how are you going to rage over Widowmaker as Zero Suit when you bought OW for PC?  That's your own fault.  It's an incentive to buy a particular version of a game.  If you missed the best version of Soul Calibur 2 because you were a PS2 fanboy, it's your loss.