While most commuter trains in the US are electric, that’s not the case for cargo or long-haul passenger rail. So “would be” refers to the opportunity to electrify those lines. Many of the tracks in the US are not electrified today.
Decent amounts of short-haul US passenger rail is not electrified, those would be good places to start. Pacific Surfliner, Metrolink, Cascades, etc are all diesel powered and could be electrified for reasonable costs.
The feds should get ahead of it and declare a rail electrification standard so that as it builds out it's all compatible.
Electrifying a thousand miles of track in the middle of nowhere that sees one train a day is nowhere near as worthwhile as electrifying busy corridors.
