Some assumptions to analyze this switch:

- Dropbox saves $50M/year in AWS costs

- Dropbox spends $200K/year (salary, benefits, equipment, SaaS, etc.) for their average infrastructure engineer

Following those assumptions, Dropbox must hire <250 additional engineers for this to break even.

Of course, these assumptions may be wrong (please correct them if so!) and this entirely ignores the unique computing needs of Dropbox's business, which may be unique vs. anything available off the shelf.