I believe that the hats are gone ?? Today I opened my profile and noticed that the line declaring how many hats I've earned has disappeared..
As said on winterba.sh that they are available till 4th of jan.. I think that was applicable for hats as a whole.
However I suggest that the hats a user has earned should remain on his profile forever. That way one can show-off and they are kind a reputation goodies too..
How about that earning hats is now closed but Hats once earned remains with the user foreveer