Nadal is the firm favourite for the French Open 2020 even if he goes in without winning a single clay title. He's capable of playing into form and reaching his stride in the second week which is enough to handle most anyone. But 2020 will be different in a way as they will have the roof and air conditioning at Philip Chatrier from what I know. So it could help certain players like Djokovic and Thiem if they meet Nadal under the roof. Nadal obviously the favourite because the French is his domain and the surface suits him but again, if he's not physically or mentally in top form and his opposition rises and meets him with a closed roof then it could get very interesting.
As for Melbourne, Nadal is probably second favourite after Djokovic on paper but if he gets a tough draw with Thiem, Medvedev, Dimitrov, Federer on his side then going through any 2 or 3 of those guys in succession could be physically very taxing. If Djokovic is in top form and waiting for him in the final, it's highly unlikely Nadal will win the title there unless he can summon his 2012 warrior mode and go one step further and shock everyone. But hard to see that happening at this age where he's not able to run endlessly for balls and defend as well as he did in 2012.
Not sure if Nadal can deal with the Federer/Djokovic dynamic at Wimbledon. Getting through even one of those guys will take him some luck, let alone going through both.
I can't see Nadal repeating his US Open feat. Seems players struggle to win the US Open in back to back seasons the past decade. And I feel the competition will be tougher the next go round.
