Being a key technology architect for it (not the core inventor), I know all about it, and then some more!
I cannot however talk publicly about it. :-(
It has been a disappointment for me as well. I had worked on it for nearly eight years. The idea was so interesting--using thin-film interference for creating images is akin to shaping Newton's rings into arbitrary images, something which even Newton would not have imagined! The demos and comparisons we had shown to various industry leaders and sometimes publicly were often instantly compelling. The people/engineers in the team were mostly the best I have ever worked with, and with whom I still maintain a great connection. But unfortunately, there were problems (not saying how much tech how much people) that were recognized by some but never got (timely) addressed. And a tech like it does not exist till date.
I do not think anything on it is being developed further.
The earliest of the patents would have expired by now.
Liquavista, Pixtronics, etc., have been alternative display technologies that also ultimately didn't make the impact desired, AFAIK.
Meanwhile, LCDs developed high pixel densities (which led to pressures on mirasol tech too), Plasma got sidelined. EInk displays have since then made good progress, though, in my opinion, are still far from colors and speeds that mirasol had. And of course, OLED, Quantum dots, ...