Yeah I don't think that would happen, they wouldn't show up, this isn't comic con where they are presumably contracted to go.I think we'll at least get Evans and RDJ on site with the announcement of Cap 3's title. They haven't really publicized Iron Man's role in Cap 3 as yet so that will be a big thing to make a formal announcement about.
I think it was just because it was DURING NYCC, so they had to make a big buzz about it. This time they've got their own thing to themselves, and they'll probably have a press release go out later today for the general public.