I work in a drugstore lab and the majority of 35mm film we get (I'm estimating about 65%) is from disposable cameras. A fairly high proportion of that consists of expired film from Konica cameras that people have had sitting around, and the horrifically crappy film from off-brand dollar store disposables. I worry that if/when the market for those goes digital then C-41 manufacture will decline significantly further. We already process the film for 3 stores in our area and even with that workload we still don't often turn on the film processor 'til later in the day.