Never moved beyond "mars tunnel research" or "excuse to delay subways," depending on how cynical you are. It's on life support in the form of totally necessary tunnel projects at other Elon Musk companies.
> Musk admitted to his biographer Ashlee Vance that Hyperloop was all about trying to get legislators to cancel plans for high-speed rail in California—even though he had no plans to build it.[1]
He knew it would delay CA-HSR and political will for it nearly died.
1. https://time.com/6203815/elon-musk-flaws-billionaire-visions...
https://x.com/parismarx/status/1167410460125097990
Note also that the excerpt in this tweet omits the subsequent page, which discusses how Musk began taking the project more seriously after being surprised by the amount of public interest. You can find the biography on libgen.