Does anyone know if a Sync 4 update will be available for current Sync 3 systems? I sure hope so because after being in a friends Silverado this last weekend it really alerted me as to how terrible the current GUI is on 3.

 

I'll go with nope. Same can be said for sync 2 which was also awful. Want an upgrade be prepared to switch vehicles.

 

Highly doubtful. A big piece of Sync 4 is the always on connection via the modem for Nav and other services. Not all existing vehicles have that connection so in my mind would not be supported.