Looks like their will be a new 177 room Hampton Inn built at 1401 S. Main St. in St. Charles, that Heart Events will use as their main event space.  The existing Heart Events space will then be redeveloped in future phases.  No renderings in the article.  Grey Design Group is the architect - who are the architects for Element in Midtown and Aloft in Cortex, but they also are behind some more standard generic hotel designs as well.  

Heart Events current space is the rounded ballroom just north of 70, overlooking the casino:

https://www.bizjournals.com/stlouis/new ... h-new.html