Need to see what this means for DateTimePicker — if "datetime" is still part of the HTML spec (I think it is), we probably don't need/want to do much more than maybe warn in development mode and perhaps add a note in the class documentation.
datetime-local sounds like it might be a reasonable alternative assuming you don't care about the timezone. Chrome has followed iOS7 in dropping datetime as well http://www.chromium.org/developers/web-platform-status/forms
Had a look at this…
:local => true