http://www.dot.ca.gov/paffairs/pr/2017/prs/17pr117.html
It would appear that single level cars will happen....
They're going to have to start raising platforms.
The ADA requirements don't magically go away because of manufacturing issues, and nothing the state or federal government does can avoid the private lawsuits. They can put portable lifts everywhere, but they'll have to schedule good long station dwells for them, and there are already serious questions about whether they're actually nondiscriminatory...
Maybe Caltrans can do a swap with Caltrain or something, since Caltrain is *already* planning to raise their platforms. Or put the bilevels on the Surfliner route and move all the single-levels to the northern routes on freight-owned track where they can't raise the platforms due to freight operator interference.
The Midwest is stuck: they will simply have to raise their platforms. It would make the most sense to start with Michigan where the line has no freight.