We will never know if Laver would have won all 4 in 1969had he played the AO and the USO on hard court. It's all speculating.
1962 was too easy in the amateur. Any multiple top players today would have won the GS given the same circumstances.
NadalAgassi: I think Serena's final slam tally will be something from 18-27. My best guess is 24 or 25 though; Nole(2010) will never win Wimbledon