I cannot find Google announcement of the abolition period of Google Apps Marketplace v1 but I thought Google Apps API authorization of Google Apps Marketplace v1 will be work until April 20, 2015 because OAuth 1.0 will work until it in accordance with the deprecation policy. However I cannot think so because Google announced that UpgradeableApp API( that is Marketplace v2 migration API) will be available until the end of Q3 2014.
I have 3 questions:
1) 20th April 2015 2) Yes, they will be removed from Marketplace after 30th September 2014 (if not upgraded) 3) Yes existing base can continue using till April 20th
All above details were sent my email to all developers I beleive, didn't you receive it?