cammace
Trunk in the US is defined as a Surface expressway: A relatively high-speed divided road (at least 40 MPH with a barrier or median separating each direction of traffic), with a limited amount of intersections and driveways; or a major intercity highway. This includes many U.S. Highways (that do not parallel an Interstate) and some state highways.

If the changes made does indeed include lowering the speed limit and doing away with the frontage road, it makes sense to relabel this highway to primary.