I've got an idea.
Why not make a UN passport? Like Schengen but for all UN signatories? With some high requirements like a minimum of a university degree and/or say $ 100 000 in the bank before you can get it...?
Benefits to passport holders: you can go anywhere and work anywhere.
Benefits to governments: you can database and track people and have free movement of skills into your countries by incentivising/promoting acceptance of the passport.