H1B- WHAT IF FIRED BY EMPLOYER WHILE TRAVELING OVERSEAS?

Sorry for posting in English as my work PC does not have support for typing in Chinese

Situation: I am on H1B and currently with Company A, the job security is in question so there is a good possibility I will be laid off. I recently got an offer from Company B, who is going to do a premium H1B transfer, the starting date with Company B is negotiable.

Problem:
I have accrued 4 weeks of vacation with Company A for which I plan to go back to China next month, I have already booked flight leaving on 10/15 returning on 11/12.

Question:

1. What if I stick to my travel plan and go back to China for one month, and then Company A fires me while I am in China, before Company B files for my H1B transfer, am I out of luck and can’t return to U.S.?
2. Is there a best way someone can suggest for me to successfully transfer H1B with Company B while still allow me to travel back to China as planed?

All discussions/suggestions welcome :)

Please advise.