The devil's bargain between tracks and slots has always been that once slots are in place the horses need the slots much more than the slots need the horses. In fact, the reality is that the slots don't need the horses at all.
In any sort of economic downturn, Racino managment will find it much more cost effective to expand slots than to continue to subsidize live racing.
Don't forget that most of these tracks are located on very desirable pieces of real estate. A little casino action, a little development, and who really needs the horses?