That's from Igor Volsky and the Center for American Progress team. Conservatives will look at that graph and say, sure, it might be nice, but those cuts will never be implemented, and if they are implemented, they'll never work, and in any case, we're going to repeal them.
It is of course true that for cuts to work, they have to be implemented, and not repealed. And it is also true that Republicans want to repeal not just the Affordable Care Act, but the Medicare cost controls in particular. And at this point, the Republican Party has not agreed on any package of reforms that would slow Medicare spending by an equivalent amount, and that they would be willing to implement. If you're a deficit hawk, in other words, at the moment, the Affordable Care Act is your best, and really only, hope.