I also don't see how Kai can't just "get used to" magic volley too. This argument is kind of dull.
Since Shukuchiho is vertical teleportation, a shot to the side is an instant point.
Secondly, nobody has returned MV. It has to be sealed by a player with a great technique or good skill.
Lastly, we know that VH isn't something that Kai can hit as freely as Jirou volleys since Kikumaru continued to get points even whilst Kai was using VH.
This could go into a tie-break, yes. Jirou will take some games and return VH at last in the last points.
Jirou can hit MV when Kai serves? How? what if he does VH and Jirou can't volley it?