Well...I suppose there are other possibilities...
1) MC's dead. The end.
2) Despite everything, the other guy dies, MC is left standing, shocking everyone!
3) MC's body plummets into the water, other guy does a victory lap - but no, MC is not dead yet! Surprise leap from below and slash slash other guy is dead!
4) Other guy is the one who does a surprise leap from below! Slash slash - but, ah! You didn't think our MC was that stupid/unprepared did you?? Other guy is defeated anyway.
I just anticipated the one that was most likely, right??
(i.e. My comment isn't serious, just making fun of the "cliffhanger".)
Oh! I thought of another one!
5) He dies. But is reincarnated again! But this time in a swords-and-magic world, where he becomes an OP 5-year-old of a noble house, with a devoted furry-eared maid, happens to save a tsundere loli princess, rescues an elfin maiden from slave traders...but really just wants to stay low-key and not attract any attention.
And then the MC died. The end.