A well thought out idea.
Runemaster was originally what the first hero class was going to be, but Blizz decided to go with Death Knight due to the Lich King xpac and all.
That being said, the closest I see to this coming out is a "Monk" class. Blizzard is currently trying to get away from duplicate power sources like mana and adding more unique class specific mechanics like Focus and Holy Power. So many of your ideas may see fruition in the form of a monk without the rune system.