Still waiting for Spotify, but saw the following from Reddit. Whether this is true, who knows, but I'll continue to be hopeful...
Important to note that changing the quality of the music at any price point changes their deals with international publishing rights organizations and labels. This is a VERY long and intensive process (it’s what I do for a living at another smaller DSP) and while I was really hoping for HiFi this year, my best guess is that Apple / Tidal / Amazon’s new models really messed with the deals that they had in place in the sense that they no longer made financial sense. Likely that they had to go back and renegotiate all the deals based on whatever subscription fees they opted to change with regard to lossless since it affects their royalty payments.
That being said, I think I have mentioned this before, I have SEEN Spotify HiFi in actual operation. Employees at the company have it enabled in beta and have for a long time. Which lends more to my theory that it’s not a technology / product issue and more of a finance / publishing issue.
Food for thought.