If you have arteriosclerosis, is it too late to regain elasticity of the arteries?

Never too late! Atherosclerosis is a process of degrees and stages. One of the very earliest, for example, is a loss of the normal dilatory response of arteries. This can be seen following cigarette smoking. Cessation of smoking can result in the return of a normal response. No matter the stage, it is never too late to engage a program of proper diet, exercise and medications as needed. Any benefit is a plus!
Atherosclerosis. Atherosclerosis is a life long disease. It is generally at different stages at the same time in various vessels. For this reason taking care of diet, exercise and drug therapy to stop progression of the disease is crucial. Some areas won't be as helped as others but you may stop them from getting worse or at least slow the process down.