Well for travel where in Denver does not really matter does it. One airport.
However, I find it frustrating that ESRI for some reason hides into on Geoconx. They often know a year in advance where the next one will be. You go to ESRI events page and they currently only show through the middle of July. And their GeoConX page only shows info on the 2019 conference.
Of course it could be that they don't 100% know at this time. I would hold off on booking travel until registration opens. If something changes you cannot get your travel money back.