Delta took over Frontier's gates on the west side of A over a year ago now. Spirit and Alaska moved over to C. United took C38 as an extra gate to help during construction at least 6 months ago. United also now operates UAX flights on gates at the east end of the A concourse, in addition to the handful of mainline flights they've operated there for the past couple years. The horrible temporary UAX structure on B concourse is finally being demolished in a few days. Ton of construction happening all over the airport, which is going to make it a headache to fly through for the next 2-3 years...but it'll hopefully be worth it in the end.