@BitFlipper: Other than seeing one in commercials, I have very little knowledge of the Sync. However, there are a few things from your description that seem to be lacking.
1. I assume "I leave my phone in my pocket, and it syncs with the car automatically" means this is using Bluetooth? The problem here is that the constant active wireless communication of Bluetooth causes battery drain. To avoid this, most people leave it off until they need it, but that means fiddling with the phone. The tray solves this problem.
2. There's no "dumb terminal" in your description. I want the hub to just be a dumb terminal that remotely controls the apps on my phone. This goes a lot farther to opening up the software I can run then having to write programs specifically for the hub. AFAIK, the Sync is an intelligent device, and I'd rather see the intelligence in the phone/cloud. Have you ever used Yelp! on your Sync? I want to use it on a hub!
3. You only mention streaming audio, but I want to be able to play all media. Obviously you don't want movies playing where the driver would be distracted, but I want to stream videos to screens in the back seat.
4. I want all of this in an open standard. It's the only way to get consumer choice and a large market. Look at the Sync. As great as it looks, how many people have this device, or anything like it? Why don't more people have it?
I'm not claiming my idea is anything radically new (except maybe the remote control of the phone, which is new, but I won't classify as radical since we've been doing it on the desktop/server for decades). Nothing I mention is something that doesn't exist today, I'm just not aware of it existing in a single implementation, much less in an open standard.