If balanced correctly I would love the changes (Nerfs to his q and e, his w being reworked into a constant source of damage/burst/auto reset). It could make his mid laning less toxic (q e for easy harass with little chance for the enemy to retaliate) and open up new options like jungling, top lane, nashors/sustained damage builds, or a tanky ap bruiser. Current kassadin will almost always just do the same mana/stack ap and burst stuff build.
tl;dr Kassadin clearly needs changes and I really hope riot goes in the direction of the last pbe patch. I found it more fun to play as and against him.