As far as I can tell, Capcom's management had decided Dash 3's fate based on their estimates of how well the game would of sold if it were released. And that this estimate was based off the dev-room membership and the Nintendo 3DS sales figures. On a superficial level, it seems like very solid numbers to hang the decision on. But seriously, how the heck is that a sure-fire barometer for sales?
Nope, that was a horrible horrible lie
First, the Dev Room was advertised as a fan submission and collaboration center. NOT A FAN OR BUYER HEADCOUNT. Naturally this fact would hinder the recruitment numbers. Plenty of people have no interest in working on the game, they just want to buy and play it. But now that cancellation has been decided, with the sliver of hope resting on "Kobun numbers", it is no wonder that Kobun enrollment has jumped over 350% (from ~4000 to ~14000) since. Also a lot of people were happy just following along with the developments and not joining in. Not like the Dev room was locked out from more casual fans who would of bought the game all the same.
And second, 3DS sales are indeed dismal currently, but did it not occur to anyone that you can't expect people to go buy a system before there are desirable games titles for it? Games that that would first need to be produced to give you reason to own it? Chicken and the Egg question for sure. Personally speaking, I was waiting for Dash 3 Prototype before I commit money into the 3DS. And having talked to many of my friends and acquaintances, I wasn't alone. There's no fun spending $250 for what is basically an expensive paperweight. And that is what the 3DS is before you get a game software on it, right?