With the rise of MMA, we know all these flippy, kicking, fancy styles get demolished by ground based fighters. Judo, Sambo, Wrestling, Jujitsu all absolutely destroy the stand-up heavy styles.

Depends on the fighter.

We just recently saw on Street Beefs how an impressive wrestler was bested by TKD/kickboxing techniques due to liver shots and finally a heel hook for a KO:

https://www.youtube.com/watch?v=Qu4GQvKgaUI

Between rounds the two wrestlers were mocking his kicks saying "All he has is kicks", but a well placed kick to the liver ends the match.

We also saw how Joaquin Buckley used a flying reverse heel-hook kick to end a match with a flush KO: https://youtu.be/1QBP7gAZIOI?t=16

It all depends on the fighter and the situation. A lot of times people not expecting the "fancy" stuff is how they oftentimes get caught by the fancy stuff.

Masivdal's five second flying knee KO against Askren is still a testament to that sentiment: https://youtu.be/I6IAz0GOCh4

EDIT: That being said, the trailer for the movie above still looks like complete shyte.