1. Post offices

Can be private

2. White House

Maybe a privately owned museum , or maybe the last remnant of the government reducing the president to the administrator of some historical monuments.

3. Capitol Building

Same as the White House

4. 9-11 memorial

Privately owned museum.

5. Military bases

Useless now, America is never conventionally attacked at home.

6. Embassies

Why? Just a place for irrational locals to attack.

7. AM track train stations (debatable)
8. Roads/Bridges/Canals

Both can be privatized.