According to @Wrestlevotes, the first NXT TakeOver event following WrestleMania 35 weekend is scheduled to be on Saturday, June 8 from The Event Center at San Jose State University in San Jose, California.
The next TakeOver event will be TakeOver: New York on Friday, April 5 from the Barclays Center in Brooklyn. The only confirmed matches as of this writing are WALTER vs. WWE UK Champion Pete Dunne and NXT Tag Team Champions The War Raiders vs. the winners of the 2019 Dusty Rhodes Tag Team Classic.
WWE has two more TakeOver events scheduled for later this year - TakeOver: Toronto on Saturday, August 10 from the Scotiabank Arena in Toronto during WWE SummerSlam weekend, and TakeOver: Chicago III on Saturday, November 23 from the Allstate Arena in Chicago during WWE Survivor Series weekend.