Thanks for the reminder. The combination of retrofits that came from the 1971 and 1994 quakes has made highway structures much safer. Nothing's perfect, though, so we have to expect to learn new things in the future - though we can now reasonably expect that there will be few outright freeway collapses. 1989 was kind of a side note; the biggest collapse (the Nimitz) and near-collapse (the double-decks in SF) was of a structure type that was very difficult to analyze and had not had any retrofit. We don't build them like that any more, and I'm pretty sure that only a short section of 280 [www.google.com] still uses that style (though significantly rebuilt) of structure.

Back (briefly) to the original topic: it's been well-explained why Mojave has no proposed HSR station. In principle, if you want to push commuter housing out that far when there's still plenty of space in the Antelope Valley, you could extend Metrolink to Rosamond or even Mojave. But note that both are in Kern County, which is not part of the Metrolink district. So at best you might get commute buses that have timed transfers to trains in Lancaster or Palmdale (or farther down the line; not all of the trains go all the way out) for the foreseeable future. HSR is not a commuter train.