First of all, I don't believe that a plot or even a script can be labeled such. For a movie to be Hitchcockian, in my opinion, it needs to look and act like a Hitchcock film, not just have themes commonly found in those films. Second, even if you wanted to use the term to describe a developing project like Craig Stiles' The Architect, which Production Weekly reports is being picked up by RKO, you're only making it worse for that film, which no way, no how will end up anywhere close to as good as a real Hitchcock.
I'm going for the extreme here, but I think of it as like you're having a baby, and before it's born you describe it as being a god-like child simply because it's another creature created in God's image. Then your baby is born and, well, it's just a regular kid. Way to get the hopes up of your friends and relatives with that baby that everyone thought was going to have super powers or rule over the universe. And way to ruin that kid's life by prematurely giving it such high expectations to live up to.
Also, I wonder: if Hitchcock was making movies today -- and for the sake of the argument, let's just say he didn't have the legendary acclaim and status that he holds in film history -- if he would even be that bankable a name, with his movies made for adults and his general lack of explosions and special effects (save for his few very broad works). He'd likely work with huge movie stars so at least he'd have that going for him, but unless he did his own sort of Dark Knight, he'd otherwise cater to a niche audience.
I won't pretend to be the biggest expert on Hitchcock's authorship, but I know having a plot involving a kidnapped wife and a conspiracy theory set in an exotic foreign locale doesn't automatically make it a Hitch. And I appreciate that /Film acknowledged that when finished The Architect is bound to be likened more to Taken and Breakdown than North by Northwest (or The Man Who Knew Too Much).
In the annoying Wikipedia entry for "Hitchcockian," there is a list of movies considered to be such, and I think only a few are even slightly close to qualifying. Some, like the De Palmas and the Carusos are merely homages. And much of the rest is just wrong man/mistaken identity/on the run stuff, which do not strictly pertain to nor originate with Hitch. There's only one director besides the real deal who I believe has made something completely Hitchcockian: Martin Scorsese. And I'm not talking about Shutter Island. I'm talking about the Freixenet ad titled The Key to Reserva. Of course, that's really just a brilliant, perfectly aped homage, too.
Are there any other works you could honestly think of as fitting the term?