Why did my neighborhood decline ?

I bought my house in 1993 in area I always have liked,lots of shops and restaurants nearby.My realtor said this will always be a good area. 10-15 years later all the shops and restaurants have closed and lower income people have moved in,the apartments that use to be good are now slums. The only reason I am afraid to put my house up for sale is what if I can't sell it ? My question is has this happened tou your area use to be good but not anymore?