VMware confirmed the dates and locations of the 2018 edition of VMworld in both US and Europe.
VMworld US event:
Mandalay Bay Convention Center in Las Vegas
August 26 - August 30
VMworld Europe event:
Fira Gran Via in Barcelona
November 5 - November 8*
* Please note that the VMworld Europe event is about two months later then this year. So if you already put a blocker in your calendar based on this years dates, make sure to update this ASAP!
I don't have any information why the VMworld Europe event is in November this year. It does not matter for the actual event, however there is less chance that you can enjoy summer days in Barcelona.