Hitchcock never made a self-conscious 'magnum opus' (thoughts on Megalopolis and the like)
Coppola's 40-years-in-the-making Megalopolis has debuted at Cannes and is *not* being hailed as a masterwork, rather it's something very familiar: a highly self-conscious, swinging for the fences, statement-making 'magnum opus', an ideas- not story-driven trainwreck that's often completely mad and cringeworthy but that arguably has enough highs and general energy to offset its pervasive dumbness thereby becoming strangely fascinating (at least if you're in the right mood).
Hitchcock never made any movies like this, although Vertigo has a self-exposing, reflexive quality about it that's always made it catnip for academics and that makes it the closest thing to a statement film that Hitch ever made. Not coincidentally, Megalopolis apparently explicitly links itself thematically to Vertigo a few times.
Some reviewers are comparing Meg to Southland Tales (2006), a notorious Cannes flop that even after extensive reediting for dvd etc. is a bizarre mish-mash of ideas and half-formed characters and free-floating images, but that film is an attempt, I think, to say something about post-9/11 and war-fever-driven America, which is relatively narrow and focused compared to what Meg is up to. Meg actually sounds more much like Metropolis (1927) which, for all its fame, was a huge financial-flop at the time, and is burdened by a lot of specific and silly/unconvincing social and economic theories in something like the way Meg is apparently encrusted with Roman history, Shakespeare, etc..
Anyhow, I'm continually struck by the number of highly risky, uncommercial, high probability of artistic faceplant 'magnum opus' movies that still actually get made. In just the last year or two we've had Beau is Afraid and Babylon, and before that there were things like the Wachowskis' Cloud Atlas and Malick's Tree of Life and art-film-world things like von Trier's Nymphomaniac, Wim Wenders' Until The End of the World, Noe's Enter The Void, and Sion Sono's Love Exposure (and maybe Suicide Club too - Sono's got a penchant for big statements). There may be in fact as many ''swing for the fences' movies made now as were made back in the supposed hey-day of risk-taking, '60s-'70s.