From the article, "Seeing Link stuffed into a tiny go kart, knees jutting from the sides, isn’t as strange a sight as it should be in 2014. After all, this is the first time in Mario Kart history we’ve seen guest characters from other games. Shut up, I haven’t ever seen a Mario Kart GP cabinet so it doesn’t count. Harumph. Unfortunately, the 90’s happened like 20 years ago, and crossovers just aren’t that interesting anymore. Random properties clashing into each other’s universes happens every other week in comic shops, and at this point Nintendo is pretty much comparable to the Marvel Universe anyway.
That said, seeing fresh new content in Mario Kart 8 - added post-launch, no less – is further proof that the system-selling franchise is evolving."