Follow-up questions:
1. If I file I539 to change from H1 to H4 before H1 expires, do I have to use premium processing?
-No. There is not premium processing available for H-4. If you want to be H-4 very quickly, you may just go to China to get the H-4 visa to come back.
If not, doesn't it take 3-4 months to approve?
-right.
During that 3-4 months, I will most likely get the I140 approved and H1 extended (via premium processing) so that I can return to work asap.
-The problem is that if your H-1 expires before you get the I-140 approval, you can not extend your H-1 anymore. If you want to be H-1 again, you need to stay outside US for at least one year.
Wouldn't USCIS get confused when they get to review the I539 and think that I want to give up the newly extended H1 for H4?
2. Following the same logic from question 1, is it possible to revoke or rescind an I539 once it is submitted?
-If your H-1` expires, you can not withdraw the H-4 application, otherwise, you will have a status gap.
If so, what is the cost?
3. Do I then have two options: A. Use premium processing on the H1 to H4 change so that there is complication once I am ready to switch back to H1? and B. Go back to China and get H4 through consulate processing to avoid the same complication?
-If you want to extend your H-1 beyond the 6-year limit, my suggestion to you is that you go to China as soon as possible to stop the H-1 clock running before your 6-year H-1 run out, then you can get the H-4 visa to come back. After your I-140 is approved, you can ask the employer to file change of your status from H-4 to H-1 with your H-1 extension beyond the 6 year limit using the I-140 approval notice. I have seen many people like you do the way I mentioned successfully.