I don't think ageing up Tim is really going to help since that will close the age gap between him and Dick, and he and Dick are more similar in the types of stories you can tell with them than he and Damian. Btw. I also think they aged up Damian to fast, there is really no need for Damain to be any older than 12 (and likely even younger) at that this point.
What they should do with Tim is go back to the type of stories they did before Identity Crisis and lean more heavily again in the Family/Highschool (or Collage) Drama aspect of this character, since him having to juggle normal live and superhero stuff was kind of his thing back than.