A few more thing that should be done:
* What about the iOS app?
* Disable translations on translatewiki.net
for the various Commons related message groups. 
* A note in the README on github about the state of the app
* A cursory web search showed me a link to this blog post of the announcement of the app quite prominently. I think it would be good to have a reply to it or at least another post on the same blog saying that we're sunsetting this app.
* MediaWiki  probably should be also updated. I've replaced the link to Google Play with the releases site on .