Wimbledon winner will skip Flushing Meadows if current coronavirus conditions persist.
Olympic gold medalist Monica Puig also signs on for 2020 season.
Nick Kyrgios calls on Big 3 to take a public stand on 2020 US Open.
The Austrian is finding some mid-season form already, and the season has yet to start.
The French Tennis Federation is planning changes for Roland Garros.
World No. 7 sees bleak scene for Flushing Meadows.
"We should just park it and start again at the beginning of next year," says former British Fed Cup captain.
