Sundial of the Infinite and end of turn effects
No.  Sarkhan stops being a dragon when your turn ends.  It doesn't matter that you have ended your turn "early" using the Sundial - the turn still ends.

The reminder text on Sundial of the Infinite makes this clear:


  {1}, {T}: End the turn. Activate this ability only during your turn. (Exile all spells and abilities on the stack. Discard down to your maximum hand size. Damage wears off, and "this turn" and "until end of turn" effects end.)