-Increase Zenyatta's base health by 50 shield points.
I don't think increased HP would solve Zen's problems.
He's fun to play as, but he needs something a bit more substantial if he's going to be more "viable".
Folks on Reddit seem keen on the idea of temporary levitation, allowing him to glide between raised areas in order to maintain high ground and perspective of the fight.
Other ideas include buffing the damage on his fully charged attack and/or allowing us to hold it at full charge indefinitely.
Increasing the timer on his orbs while outside line of sight could also help. Even from 3 seconds to 5 would allow him to "fire and forget", and stay on the move while still helping team mates and hassling opponents.