Not that I know of. ChromeOS still uses it and though Ubuntu is phasing it out, they haven't completely gotten rid of it as a session manager yet AFAIK. They need to support it for a few more years anyway due to 14.04 LTS.

That's exactly the difference between deprecated an obsolete. The former means it's on it's way to the latter. Putting work into upstart just means you'll have work migrating to systemd in less than a year or two.