"They will not tolerate even the slightest bit of fanmade media"
Okay, but what about the 99% of fangames that haven't gotten takedowns? Super Mario Bros. X, Super Mario 63, Super Smash Bros. Crusade, Super Mario Flashback, Dream Crafter, Heaven Studio, and all that, for example? Plus, someone from a popular Mario fangame site has said that it's only a small percentage of fangames that get taken down, and usually it's because Nintendo's working on a similar idea.
Trust me, I think MKF is safe, unless Nintendo's planning to put Sonic, Mega Man, Samus, etc. in their next mainline Mario platformer.