It won't happen. I think the ending in Inuyasha will be as follows:
1) Kagome is going to somehow turn into a demon and stay with Inuyasha in the his time and have lil demon babys.
2) Kikyo is going to except death and DIE after seeing Inuyasha is happy with the one he has.
3) Sesshomaru is going to continue to try and take the Tessaiga....and lose somehow every single time.
4) Miroku and Sango are gonna get a divorce LOL j/k. they'd prolly live next to Inuyasha and Kagome wherever they live and fight along side the two still whenever the time comes.