[bdfh42]

If your boss was fired for justifiable reasons then perhaps staying is an option. If it feels that his/her departure was for financial reasons or just plain whimsy then it is time to explore the other options - as fast as you like.

[hga]

It sounds likely that three critical people separating in just two months is more likely to be due to the latter class of reasons you cite. At the very least figuring out why, and why they aren't getting replaced quickly, is critical, and if answers to those questions aren't forthcoming, indeed get out ASAP.