Once you change your non-immigrant status to F-1 (an academic student) you will no longer hold the H-1 (special skills worker non-immigrant status) any longer. And, If you currently have an application pending with USCIS for a green card, changing you status MAY adversely effect that process, so be careful about changing your status to F-1.
Now, most graduate programs take either two years to complete a Masters or four years to complete a Ph.D. program. It is then, at the time of graduation, that you will either be applying for a period of practical training, filing for an H-1 non-immigrant visa with your employer or perhaps applying for adjustment of status for permanent residence in the United States - if you haven't already.
Frankly, given the fact that Congress is in the process of ..or being pressured to change the entire structure of the non-immigrant programs as they now stand, no one can really accurately tell you what to expect from three to five years from now. In the meantime, keep informed through your foreign student counselor at your college or university about the changes in the law.
But before you do anything, please consult with a well qualified immigration attorney about your options. They can really save you a lot of trouble down the road!