Unconfirmed yet by VMware but according website Conventioncalender.com VMworld US 2019 will be back in the Moscone Center in San Francisco.
Dates are August 26 to August 29, 2019
This is not a big surprise. VMworld moved to Las Vegas for 2016, 2017 and 2018 editions. Likely because of renovations of the Moscone Center.
VMworld 2019 Europe dates and location are also not announced by VMware yet. Very likely this will be Barcelona in November again.