I don't think that DL buses people in SEA...yet. I have had them drop me off on the tarmac and walk into the S Satellite before. Like others have said, I think it is a new gate with a jetway and everything - they split a few gates in two to add more capacity. 1:40 should be a very comfortable amount of time to make a connection even if you are an hour late, but track the inbound flight into SFO. If that looks like it will be significantly delayed, get to the airport early and they will put you on a different flight (assuming space is available) to make it into SEA in time. They run flights frequently.