The pathway is fundamental alteration of the baseline conditions for rail in the USA.

At present they are in the standard corporate structure in the USA, where fiduciary responsibility is strictly limited to shareholders. They are constrained from making investments that do not maximize returns, which in the USA has proven to be short-term returns, not continued existence. US corporate fiduciary responsibility is most extreme globally in this regard, with most other countries having more responsibility to other stakeholders.

Further, the USA is unique in that the corporations own the tracks. This has had pros and cons, but for electrification and combined with the fiduciary responsibility means that electrification is too expensive to justify.

Those conditions have to be broken or 'respected'.

One model is nationalization of the dying corporations, or at least their rail assets. The USA takes the critical 50% over as national infrastructure assets, electrifies them and legislates that the rail companies use the maintenance cost relief to put pantographs on their trains and figure out the operational changes.

Another model is a grand deal where the USA gifts the electrical infrastructure to the rail companies for the critical 50% of tracks in return for their commitment to electrifiy their locomotives.

I don't see either occurring for the next 20 years.

There's a faint hope alternative. One professional conversation I had this year was with a very well funded startup being considered as an investment by Israel's biggest VC (my client) which was assessing an electricity-as-a-service model for rail with microgrids and low-operational impact cantilevered overhead wires along with batteries on trains to bridge the gaps. The idea was to avoid anything except operational costs for the train operators, and have those be equal to or lower than diesel. They didn't appear to have considered going uphill in their modeling, so their energy requirements and gaps were off, in my opinion. Perhaps they'll succeed.