An unexpected revival of Firefox OS
FirefoxOS was one of those hail-mary longshots that you always thought would be destined for failure but you had to respect the fact that they had the guts to attempt it anyway. (Though to be fair, Rust was the same sort of project, so sometimes long shots pay off.) It showed that Mozilla understood the existential risk of ceding control of the platform itself to your direct competitors. I'd love to see it come back and I'm sad that I never got my hands on one of the original phones.