The answer is no.
Not only haven't we heard about any plans for a new casino, large or small, we've actually heard the opposite: Station Casinos recently announced that it's selling several large parcels along Boulder Highway, which it was holding with an eye toward developing them into casinos. In selling them, Station stated that it saw limited potential for growth on the east side and had opted instead to focus on the west side.
Also, don't forget that the Castaways (orginally the Showboat), one of the largest casinos on Boulder Highway, closed last year and has yet to reopen.