I'll be very curious to see how Coinbase pull off a banking relationship. You can have all the regulation you like but it counts for nothing unless the banks want to play with them.
I guess they are a lot bigger and sleeker than anyone else who attempted it. They may also be hopelessly overconfident and never manage it.
This is the crux of the matter. Even those that have managed to get a banking relationship haven't managed to secure it for long (e.g. Safello).
Honestly, the "regulation" bit is mostly nonsense and really just marketing speak (in my opinion, considering the FCA don't regulate Bitcoins and there basically is none). However, a banking relationship will change the game if it is sustainable.