also (an argument which I personally don't like because I prefer encryption never to be broken) assume in 20 years the NSA will decrypt my message of today that I will meet friday with friends at the cinema will the infirmation even have any value? Information has a halflife and in 20 years I won't care that the NSA knows my seating for Furiosa.
Assuming hypothetical quantum computer breakthroughts that don't exist yet.
Assuming not using quantum mitigation which already exists