Well, I guess the commitment to Amazon was that Route 1 / Richmond (formerly JD) Highway would be lowered and become an "urban streetscape." I suppose for Amazon that makes for some easier footpaths connecting the CC buildings rather than the underpasses at 12th, 15th, and 18th. Connects them more to Boeing's campus to give it the Seattle feel.
Along these lines, i don't know who owns the old American Motel lot. How that is rebuilt probably is dependent on what Route 1 looks like. It is between one of the HQ2 buildings and Route 1. I sort of assumed residential, but maybe they push through the street that's between the HQ2 buildings (14th?), extend it down past Route 1 and connect to Bell?
