Andy Murray, on Sunday, ended Britain's 77-year title drought, after winning the 'prestigious' Wimbledon Championships 2013, by defeating top-seed Novak Djokovic in straight sets.
In an interview with BBC Sport, McEnroe said, "I'd be surprised if he doesn't win at least six majors. He's come into his own and there's a lot to look forward to."
"This is a big thing. This is a new face who has stepped up in a big way.
"It's clearly important for all of tennis, but here it's monumental. Every year people ask the same questions -- now he never has to hear Fred Perry's name again.
"When he pumped his fists at the end, I thought he was doing it to Tim Henman in the BBC commentary booth because he had some mutual respect for what Tim had done himself.
"But he said it was a little defiance towards the press. He's shut them down and will never have to hear people again asking whether he can win it. Hopefully he'll get the respect he deserves. He looks pretty darn good to me," the former world #1 exclaimed, as he signed off.