No, not like a clone. As they explained in the episode it is her taken out of her time stream at the last possible moment. She still has to go back because her death is a fixed point in time but she's in no hurry. There's at least another example of this in fiction that's nagging at my memory but I can't quite place an exact example.
She's finished her story arc of becoming more and more like the doctor by stealing a Tardis and running off through space and time with a companion. It's a nice way to go out. I wondered if her new status quo provided a more straight forward way for her to become the Impossible Girl. She can travel through space and time and cross paths with the Doctor many times over. Oswin Oswald and Clara Oswin Oswald though both seem to be their own people so maybe not.
I'm also curious about the end of the universe. We've got Me hanging out in the ruins of Gallifrey. We've got Professor Yana helping to build a rocket to take surviving humans to Utopia. We've got some... thing... outside knocking on Orson Pink's door. Was that Me? I've always assumed the Doctor took the Master's body back to Prof Yana's planet to bury him at the end of season three, at the end of time, so the woman taking the ring? Who's never been explicitly identified? Was that Clara and/or Me? The Master had to come back in order for him to connect Clara and the Doctor. Were they maybe doing some predestination time loop stuff?
Rassilon didn't quite "just walk off". There was a military coup. A bloodless one, but for sure the military turned on their leadership. I just thought it a shame that since he had regenerated since his last appearance in Ten's last story, I didn't recognise it was meant to be Rassilon until he left.