I wouldn't characterize it as wishful thinking so much as a reasonable expectation. I'm not an idiot, I understand what is going on with the line, the industry, the economy, the seasons, the rotation of the sun, etc etc. But this is the very definition of an iconic ship, at least as far as the current media goes. It is a gaping omission from the Rebels toy line-up thus far. The damn thing is practically designed to be an ideal vehicle/playset too, from the cockpit to the living quarters to the docking station for the Phantom.
I get that not everyone is a diehard fan of the show or the toys...that's totally cool. It's not for everyone. But I would not go so far as to imply collectors who are big fans of the show are unhinged from reality for assuming this is going to get made at some point soon. Maybe it's already under development and will be unveiled prior to Christmas, when the second season (which has been confirmed) will be airing. It's not like everything is going to come grinding to a halt come September and all they are going to make is TFA stuff anymore. Hasbro is on record as saying they plan to continue supporting Rebels, so I think it is fair to expect more to come. And there's not that many other vehicles there to choose from at this point.
I don't think it has anything to do with the movies, or being in a movie, or whatever. Eventually, IMHO, it'll happen. It's a major part of "The Canon" now. (It took them awhile to get to the MTT too...)
Just my two cents~