Maybe I'm just conservative at heart with my items, but I doubt it'll ever see widespread use. Mainly because it sets you down this drive to counter things - kritz hard counters qf absolutely, so you just see this paper rock scissors game of who has what kind of medigun.
I imagine it *might* find its way to teams that manage it well, assuming it's not banned, but in general it's not going to replace uber or kritz, simply because uber actually makes you invincible and kritz will destroy even teams with uber sometimes. I also doubt that the medic can ever truly gain control over where he is going - especially since the game tends to revolve around chokes, not to mention that you generally don't want to move your medic in that deep. Yes, you could use it to escape bad things, but since the med still takes fall damage normally, you're doomed to suffer minor annoyances in that capacity as well.
Assuming it's not banned, it'll be seen more than it was, but I doubt it will ever see widespread use, simply because kritz counters it absolutely, as does say, a sticky trap or any 2 classes that hit directs (although this used to be true of any class that was being healed - other than heavy, this is now only really true for the medic himself/herself).