Depends on the language. Malayalam movies have consistently maintained their quality post 2008 after the massive Golden age between 1985-1995. Some of the Bollywood hits (Hera Pheri, Bhool Bhulaiyaa, etc.) were all made from much older Malayalam movies of this era.
I feel that Kannada movie quality has substantially increased. There has been not much difference in quality in Telugu and Tamil movies.
Mainstream Hindi movies have mostly become shit. Bollywood cannot copy stories from other languages now as movies are launching simultaneously in every language. That said, some non-mainstream movies are awesome. Unfortunately public support in theatres is low.