This is my vote :D
1. Female/Female Kpop Collab
Who: Gummy/Lee Hi
Genre: R&B ballad
Theme:Lee Hi is coldly singing about not being sorry for taking Gummy's man and Gummy is singing about how she'll cut a bish.
Why: Only female pairing I think I'd get excited about really. It would be interesting.
2. Male/Male Kpop Collab
Who: Bang Yonggook (B.A.P), Rapmon (BTS), Zico (Block B)
Theme: Cypher a.k.a Throwin down the gauntlet (tentatively called BangMon & Co.)
Why: I see it as just a great collab to go HAM on everything and show the difference in style between them.
3. Male/Female Kpop Collab
Who: Joon (MBLAQ) and Ga In (Brown Eyed Girls)
Genre: Pop/soft ballad
Theme: Seductive love/hate relationship with the tearing of clothes, banging up against the wall, real kissing, and bed scenes
Why: Ga In is great at acting. Joon is great at acting. Neither is afraid of sexy time. This is the formula for a controversial video gone right.
4. Kpop/Non-Kpop Collab
Who: Jaejoong(JYJ) and Gackt (or Hyde)
Why: Why NOT? J-rock touching my kpop fandom is a blessing at almost all times, but this would especially be the cream on the cake (for my funeral because I will die if this happens).
Sources: Soompi/Tumblr/MTV K/Kpop Collective/ Image Shack/Blogspot/Blogspot/Tumblr/Tumblr
Mods: Crossing my fingers it works this time. Thanks for the text area coding. :D