It depends on the cause of the diffuse hair loss. If the diffuse balding is telogen effluvium, then you may get all your hair back (depending on the cause of the T.E.) If, on the other hand, the diffuse thinning is male pattern baldness, then the answer is that you are bound to lose hair.
That is why it is important to see a doctor or dermatoligist to get your hair loss diagnosed: so you can choose an appropriate treatment. male pattern baldness presents in some people as diffuse thinning.