Maybe so. That's part of the reason why I kind of hope the writers include her in a future episode of Rebels just so we have some gauge as to what happened to her after she walked away from Anakin and down the steps of the Jedi Temple. With the colossal population of Coruscant - a world teeming with tens of billions of inhabitants of different species - I could see an ex-Jedi who'd given up on the order keeping her head down and eking out a life under Imperial rule, doing what she could to prevent her former identity as a Jedi Padawan and the apprentice of Anakin Skywalker from being discovered by those around her. She's Force sensitive, so it's possible Vader could pick up on his old apprentice's Force signature and realize Ahsoka was still alive - and potentially a threat, sending troops and agents to eliminate her. But who knows. Were things that cut and dry, a Jedi Knight as immensely powerful and well-known as Obi-Wan Kenobi shouldn't have been able to spend twenty years as a kooky old hermit on Anakin Skywalker's former homeworld, and living not all that far from where Anakin did as a youth, close to an Imperial garrison and at least two significant Outer Rim spaceports.
Truth is, things are only as simple or as complicated as the writers of this universe decide to make it. She could be running for her life for all we know, hiding out where she can to avoid Stormtroopers and/or the Inquisitor. She might have been killed at some point, perhaps even at Darth Vader's hand. Then again, she could have successfully made it off Coruscant and to some distant system away from anybody who might have suspicions about her past. It's going to be fascinating to see what the writers decide to do with her character, if anything at all.