A while ago Opera updated the Opera Mini servers with a newer version of the Presto rendering engine. If I remember it right, it previously used the Presto version also used in Opera 11, and the new version uses the version of Presto that Opera 12 used.
But you can't use that version forever, after a while the compatibility will so bad, that no one can't use Opera mini anymore. So my question is, will the development Opera Mini end, or are you going to work more on the discontinued Presto engine? Or are you going to make a new one based on Chromium?