In USA PS4 had X1 competing fiercely for sales. WW would be a harder battle.
Switch is at 5,778,903 WW for 2019 and PS4 was at 5,246,935 WW for 2016. Switch is winning NPD by 9.7% so far, and WW by 10.1% so actually in WW comparison it's doing slightly better.
PS4 sold 17.5m in 2016 and Switch will sell 19.5-20m this year. It's the legs of the PS4 that are going to be the killer.
Predictions (Made July 2019)
LTD: PS4 - 130m, Switch - 110m, XBO - 52m 2019 : PS4 - 15m, Switch - 18.8m, XBO - 4.8m 2020: Switch - 22m (Peak Year)