Which brings the question, what is the bare minimum number of humans needed to keep the website running?
No customer acquisition, no new features etc.
One thing to think about is you're talking in technical terms. 100 dudes could "do the job" maybe. But an equally interesting question arises: of all the people who left, how many were managers?
If there are more strategists than "doers", you got a top-heavy organization. Those usually can't sustain themselves because no matter how good the plan is, things actually need to get done.
A fascinating case for future business classes in any case.