which music genres do you think will never merge, due to the enormous differences? i think:
-jazz black metal(the technicality gap is incredible)
-power death metal(sure, some bands tried, but you just can't, since you'll either get more melodeath or you'll just end up writing some heavy power stuff)
-gangsta rap+"-core"(gangsta rap is all about "bitches, shootings, and cops" rapping over a simple drumbeat, while hardcore is more based on stomp rhythms and moshing riffs, and don't get me started on grindcore)
-country+every metal genre(country is mostly about a dude with a guitar doing some simple chord progressions and singing in a redneck voice about how he took the horse out for a ride or stuff, while metal, in musical essence and lyrics, just couldn't be more different)