This is exactly how Facebook's onboarding process works (at least in engineering). You spend 3-4 weeks in "bootcamp" classes (React 101, IOS 101, etc.). After that, you spend another 3-4 weeks auditioning teams -- you sit with teams that have open headcount for a week, attend their meetings, and work with a mentor on a coding project. Once you decide which team is the best fit, you "graduate" bootcamp and join them.
It's not perfect -- if there's no open headcount on your dream team, you'll have to pick another, but it's the best onboarding process I've seen from an employee standpoint.