It would probably be a partnership between a European and N American manufacturer. The underframes, draft gear , control cab and some truck components on European locomotives are unsuitable and potentially illegal in the US. US firms don't have the experience or production lines in the electrical systems. So it would be a conventional "US" AC locomotive with a modified US hood covering European electrical gear.
Since they would be extremely limited production runs, they would be hugely expensive. On the other hand, since the majority of the engine was made of stock locomotive parts, it would have performance that wouldn't be much different than a regular AC diesel it was derived from. And since only part of the route was electrified, it would require 2 sets of locomotives per train plus the delays to change power, another economic disadvantage.
Going to the other end of the country. The MILW had a very poor infrastructure and relatively small operation and abandoned electrification, while on the former PRR they had a huge, robust infrastructure and a large electrified operation, and they still abandoned freight electrification. Don't underestimate the economics of having to change engines. Right now one set of engines can pull a train from the west coast to the east coast with only 2 brief stops enroute to refuel.