Here's a news story I just found about the closing. Apparently they want to focus on the MontBleu across the street.

When I was at the Horizon last May, I hated it. The casino was outdated, the staff less than friendly, and the room was like sleeping in a broom closet. I ended up spending most of my time (and money) at Harvey's, Harrah's and MontBleu. Ah, fond memories.....