You only have to casually witness the art world - even just at a local level - to see that speculation by wealthy buyers sustains it, and also, that it costs a lot to produce art as a professional. So maybe without patronage some level of art would exist, but it wouldn't exist as a community without people ultimately paying a lot of money for work.
Furry porn producers would continue to make a mint though.
The fact that patronage can be good for the Arts is not in question but if you do a search for great artist that die in poverty and unrecognized during their lifetime you will find plenty of very famous name.
My rapid search brings me El Greco, Claude Monet, Johan Sebastian Bach, Franz Kafka, Johannes Vermeer, Edgar Allan Poe, Herman Melville, Vincent Van Gogh from http://www.toptenz.net/top-10-now-famous-artists-died-ignomi... ; I think it wouldn't be fair to consider them minor artist.
Art co-exist with society for more that 17,000 years if you consider Lascaux. It doesn't make sense to reduce Art to profitable or bankable Art.
To produce Art can be expensive and can be cheap, without money you will not produce beautiful marble statue or Faberge eggs but Art doesn't do be expensive.
Furry porn producers would continue to make a mint though.