Since you put F2 as an option, I assume you have ur spouse in F1 status. Under the circumstances, F2 is the best option. The time you get fired, you can immediately apply for F2 as long as your spouse is in valid F1 status. Applying for F1 may take time since you need to apply for school and get I-20 which is the lengthy process. Once you are in F2 and later on get another job, it's not a big deal to apply for H1 again.

 I would suggest you to go to F2, the best way. Apply as early as possible for the change of status, but you have to show the bank amount greater than the amount shown on your I20. 

 As far as I know if your H1B gets terminated, you are out of status. I am not sure if there is any grace period after H1B termination. Other Sajhaites might be able to share their expertise on "grace period".  So termination sounds like a bad idea. Say your H1B did get terminated, if you want to get F1/F2, you should do it immediately. USCIS may not approve your change to new status if there is a significant gap between H1B termination and you applying for a new status.

If you want a Change of Status(COS) to F1/F2 while in H1B, may be F2 is the quickest/easiest. I do not know much about F2. But I do know about changing status from H1B to F1 because I had to do it.
To change status to F1, first you have to have an I-20, then you have two options.
1. Apply for Change of status from within US. This process may take upto a few months. Just because you have an I-20 does not mean your status automatically changes to F1. You have to fill out paperwork to do so. And while your case is not approved, you cannot join school as a FULL TIME student. You are allowed to take part time classes on your H1B, but no full time student status.
2. Go outside of US, apply for a new F1 visa with the new I-20. Stamping of a new visa on your passport automatically changes your status to F1. I chose this option.

Hopefully this helps.