Diesel won't be completely eliminated in USA for a long time but I think this 2036 California policy has huge implications to reduce the 'last mile' share of such trucks dramatically via rail. With the initially high cost of EVs there will be even more economic incentive to take goods from California ports and put them directly onto rail for say, a journey to rural Indiana via Indianapolis. Or really just anywhere outside CA, but the further the better once you're on rail because the miles are so cheap, thus minimizing the last mile share for trucks. The primary disincentive for intermodal is, well, the cost to switch modes.
There is also a nationwide growing popularity of 'inland ports' where goods are brought by rail from the coastal ports to a specific transfer point operated by the port authority relatively nearby. This avoids fewer over the road truck miles but an advantage is that the port authority can use dedicated rail shuttle service with high frequency which means very high throughput. The east coast has a few that help goods dodge the highly trafficked I-95 corridor and reduce coastal port congestion.