I predict this will be as successful as the irony mark
I don't think you can patent punctuation.
Never underestimate American intellectual property laws.
No, but the thing about American laws is that they work only in the US. Well, most of the time, anyway.
Basically, I think more nuanced punctuation is an excellent idea, and it certainly could
catch on, but not as long as someone is trying to cash in on it. If the marks in question were simply added to the various official character sets (as defined by whoever does these things. ISO? ANSI? W3C?) then I'm sure people would start using them.