Believe me if you have the first thing the latter things will eventually follow. At least in the EU "universally mandated" has been a reality for a very long time.
That's the definition of the slippery slope fallacy. Those things need not necessarily follow, that's the point.
There are many places with mandated ID. Can you mention one in which any of the others on the list have "eventually followed"? You are presenting speculation as unavoidable fact.
Then why haven't they done that already? "Hold your encryption key in escrow" is perfectly feasible without a national ID system.