That isn't what the comics tell us. Gordon came to Gotham around the same time that Bruce came back to be Batman. Batman: Year One tells us about Batman's entry into Gotham, but it also tells us about Gordon's first year in Gotham as well. Gordon being present as an officer during Bruce's childhood was made up for the Nolan films.I hope Thomas and Martha show up as supporting characters.
Maybe the mob tries taking down Thomas and we get to see how he and Martha met.
Yeah, yeah, TV show doesn't have to follow the comics, but I don't think they'd push Gordon's generation all the way back to being as old or older than Bruce's parents. Not if they want it to connect with the Batman mythos while still having Gordon as the hero of the story. With how the Internet reacted to this news, I suspect that they'll be incorporating more and more elements from Gotham Central, even if that wasn't their original goal. Even if Batman doesn't exist during the run of the show, I fully expect it to be happening "just" before Batman arrived in Gotham, not decades before. They'll be using the villains who are Batman's contemporaries, even though Batman just happens to have not come by yet.
So you see this show using characters like Mad Hatter, but yet it's a full couple of decades before Batman will be on the scene? You think that makes sense? Not that I condone it, but I could understand wanting to end the series before Batman exists at all... but ending the series a minimum of 12 years before Batman exists? That would be depressing and kind of pointless to the Batman mythos. It'd be like if instead of Smallville, we got a series about Jor-El on Krypton and the show ended when Krypton blew up.End the series with Thomas and Martha's death.