Maybe they will make him The Heretic, but in Gotham he is a clone of Bruce, not Damien.

You know what, I don't think Bruce will become Batman in this weird universe. There will not be a Batman, but Gordon will probably fill in his shows, by turning into a armed vigilante\commissioner.

I thought that too. I don't think clone Bruce is that bad character wise, and if something were to happen to the real Bruce Wayne But then I never read the comic books, and I'm sure they're going somewhere else with this.

Bruce will eventually become Batman when he toughens up and completes his training while the doppelganger will most likely be Owlman (Lincoln March/Thomas Wayne Jr.) since we are dealing with the Court of Owls, not to mention that he doesn't seem to mind beating people to within an inch of their lives should the need (or impulse) arise.
Besides, I really doubt that the writers would kill off Bruce, he is to important as a character.

RIght!!! THat's exactly what I thought maybe clone Bruce becomes Batman and the real one dies lol

I love the show, but I don't see the show lasting until Bruce/David grows up into adulthood. If anything, I can see the show doing a time jump and getting an older actor to start training to become Batman, but I don't think this show will actually give us Batman because he's not the main focus.

David Mazouz is currently 15. I'm sure if the show lasts into his adulthood, they will start him in a strength training program to help him build up some muscle. Right now, I don't think it is necessary for the show or the character.

Will he weigh more than 140 pounds??

I doubt Bruce will ever become Batman.
Im expecting maybe a tease in the very last episode like in Smallville.
Have you ever noticed that the people who say "DC is for adults and Marvel is for kids", are kids?