I don't agree that filmmakers wanting to win Cannes is the major factor contributing to the homogenization of the supply of film, but that rather this is a symptom of an increasingly globalized culture making unique perspectives more difficult to attain. Is a modern day Tokyo Story, a Pather Panchali or a Grand Illusion possible today, or is it, like these films suggest, lost like small shops are to big corporations such as Wal-Mart? This isn't to say that smaller production companies have been usurped by such companies, though to some extent they might--I truly lack any expertise in the field to make any such judgement, but it is to say that these cultures have been, and that, as you suggest, the methods or rules by which films are created have been.
Quite strong evidence to the contrary and in line with my opening premise are the recent films of Apichatpong Weerasethakul and Terrence Malick. The former has managed to put to screen profound intricacies via innovation and creation of mechanisms by which narrative can operate, and by which, as Dheepan indicates, others are--thus far mostly failingly--trying to operate with as well.
In a bar, after an evening of debating in the debating club
, I got into an impossibly long, impassioned argument as to why The Stranger by Camus is trash (it is), and in doing so I managed to give a moderately comprehensive account of why the above films are better, but I seem to have forgotten a lot of it. The core argument, though, was predicated upon there being little aesthetic value in 1) directly presenting themes and doing so 2) in excess as Camus did in his first lines: (Maman died today. Or yesterday maybe, I don't know.) (ugh). Apichatpong (and to a lesser, but still major extent Malick) 'hide' these themes behind behaviours almost entirely contradictory to our expectations of what those behaviours would be like given the set of circumstances presented to us. Apichatpong uses described contrasts and the outermost symptoms of root mechanisms Camus would have directly pinpointed as if they had material value in the operative structures of the narrative, creating multilayered interaction between a bunch of said symptoms (and hence themes) to truly elucidate the meaning and significance of those themes. Inland Empire, relevant due to the cheap camera Lynch used to shoot the whole thing, likely as a means to enhance the power of the middle finger he presented to those in the Inland Empire and Hollywood, would also have been included as strong evidence if it weren't already 11 years old.
Having noted all that, I actually am fairly optimistic in regards to the future of cinema. Simply too much power resides in the decrease in costs and barriers to make film and the inevitable increase in wealth of nations and the corollary of increased demand for all types of cinema, even those types you would derive more joy out of.