The whole plan that Amazon has includes miles of new roads and possible lane adding to existing roads, entirely new homes, apartments, schools, shopping areas, and other city planning requirements. It won't affect Arlington very much because the plan on building section of the city from ground up.
Unlike many companies, 50000 new jobs is a big ticket and they need to plan a great addition to existing infra (public and private) to move.
@foodtruck the ecosystem is what concerns me. What other options are there for tech industry jobs when, inevitably, people decide they don’t want to work at Amazon anymore? At least in places like Seattle, NY, SF, you have options.
DC traffic is times worse than Seattle. Toll roads everywhere. Not mentioning there’s nothing to do beyond the city: no mountains or ocean nearby. Stupidest decision, if they make it. Amazon should have started HQ2 in Bellevue.
Also coming to DC is way less disruptive than building something in say Raleigh or Austin. Georgia is too conservative, and NYC and Boston already have established tech so Amazon can be King in the area.
In terms of talent, it's not like there aren't people smart as fuck outside of SF and Seattle. Also, you mostly need people in the bulk, worker bees.