On open carry versus concealed:
First off, the main body of case law regarding "carry" are a series of 19th Century cases that all say "concealed carry can be banned so long as open carry is legal". Most or possibly all of them are listed in Heller's footnote nine.
This logic got repeated very recently in 2003 by the Ohio Supremes in the Klein case. Gunnies sued for CCW permit access without doing the "special deputy" thing. (Officially there was no legal CCW in Ohio - in practice though...)
We "lost" - but in the decision in which we "lost" (quotes are very relevant here!) the Ohio Supremes said "OK, no right to concealed carry but that's OK under the Ohio state constitutional RKBA bit because everybody knows open carry is legal".
Except guess what? NOT everybody knew that. The gun-grabbers all looked at each other and went "oh $^&%" because the usual practice of filing "disturbing the peace" charges just came to a crashing end.
Which caused gunnies to do open-carry rallies that annoyed their way into a reasonable CCW system about a year later.
And that's why the argument between open and concealed carry isn't really important. We have more case law supporting open carry than we do concealed (the Heller footnote 9 cases plus Klein and some others). We now know that if we get open carry, concealed will rapidly follow.
Now, there might be an interesting twist here, one that is specific to New York or Chicago. IF the US Supremes goes the same way as Klein and supports open carry when concealed carry is restricted or banned, and there are huge open carry rallies in New York and Chicago, I believe it is very possible that one of the twitchier members of the NYPD or Chicago PD will shoot somebody. Sorry, but both departments are chock full of crazies and rank only slightly higher than Puerto Rico's state police for overall professionalism. Hold an open carry rally in Times Square or whatever Chicago's equivalent is and one of the "finest" will go stark raving bonkers, law or no law.
And that will lead to a whole new problem: if obeying the law is going to get you killed by what amounts to a criminal gang, do we THEN have an immediate right to concealed carry?
Now...some will take issue with what I'm saying here but...folks, not only is there epidemic corruption in both departments, but they have been systematically programmed against civilian arms. One look at NYC's "stop and frisk" program will tell you that they've also been told to trample the Constitution, by the numbers. Don't make me post a link to Frank Serpico's blog (yeah, he's still alive and actively writing and one guess as to his favorite subject...).
Predicting the results of a sudden RKBA loosening in those towns is not difficult.