Sorry, but I don't think we will never find out what is really going on simply by asking the companies involved. (Even with pretty please, sugar on the top an' everything.)
Tweeten appear to follow the same theory as Saluc/Aramith when it comes to public relations - They have very obviously made changes in their products over the years but do not want to admit to it. I guess they think that consumers could expect actual responses to their complaints or requests to change it back to how it used to be. So they just keep telling us nothing has changed and please go away. Also any real information released could be used by their competitors against them.
There is no question in my direct experience that there has been a change either in formulation and/or manufacturing process of Master's Blue. When I first came to the USA 11 years ago most all the Master's Blue was a lighter blue color and noticably smoother in texture, and tended to apply a bit faster and leave a thicker layer of chalk on the tip. (Not always a good thing BTW) At some point (and I personally think it happened before the flag was put on the label, so in a sense the Tweeten rep may have been telling the partial truth) they switched to the current version, which is a darker shade of blue and is a bit more gritty and less smooth in application.
I generally purchase Gross boxes of Masters and could see no change of the labels or packaging. I've never had a box that contained a mixture, only one or the other. Other people I've spoken to (and contributors here) have noted this change too. Given that boxes of chalk can sit on warehouse shelves for months or years it has taken a while for all the older, ligher blue stock to work it's way out of the system. I haven't personally seen any for years out here in darkest Southern California but other regions may vary.
If I had to guess I'd say Tweeten worked out a small change in formulation and/or manufacturing process for Master's Blue that saved them money. They enacted this change silently and continued selling the same product under the same name for the same price. They still have a very large market share so clearly this tactic works for them. On this basis it is entirely possible the "new" super chalks are simply revisions of their older forumulations of Master's Blue. You'd have to assume there are some kind of contractual agreements in place to stop Tweeten simply marketing a "super" chalk of their own at half the price or they'd have done it by now. Of course they could also be getting a cut of the sales revenue from these other chalks for all we know.