The Blast looks more capable than I expected, judging by the video. But I have to side with those who find it a little disappointing. Same goes for the EVO RMK. I understand the argument that it's too expensive to build a whole new chassis, and it would be a hard fight to get the accountants at any company to pony up for it, but I believe it could be profitable. Using a lot of components designed for a full-size, full power sled, like the Blast and EVO do, means you're stuck with certain dimensions and excess weight. It might be better for small riders, but it's nowhere near what a clean sheet design could be. Consider that if you took a used Pro-RMK 600 and changed around the seat and bars for a smaller rider, you'd have a sled that's about the same weight as the Blast or EVO RMK, probably won't be much harder to ride, is much more capable, and at the same price. I'm not sure why anyone willing to do that work would buy the Blast or EVO. I'd say Cat has ventured more and has a better lineup, but if Doo were to come out with a new sled a la Freestyle, the Blast and EVO would be history.
You pretty much defeat your purpose here when you decide to use a full-size chassis design and/or raid the parts bin. The only exception I'd make to that is that you could use one motor and clutch/drivetrain across the line (Polaris did ok selecting a fan twin, but the 550 is ooooold!). I don't see any reason why 350lb wouldn't be easy with a 3/4-ish scale, single-cylinder, and 370 with a fan twin. The Freestyle is in the right vein, and the segment is so neglected that they hold a lot of value. Obviously I have no hard numbers on the market – for all I know sleds like the Freestyle and Indy Lite did nothing but lose money. Still, the best way to bring new people in is to lower the price point while not killing the fun. Obviously Cat and Poo are trying, but they're doing it mostly with existing parts, and the result is kind of weak. The other path is to sink some major R&D costs and hope the market comes to you. I'm not just talking about making a pure "kid's sled," but a small/lighter chassis designed to scale around a smaller rider (tween to adult) and modest power and track (<100HP, ≤144, roughly). I can't ignore that it's risky, but done right, it would own the segment and grow it to some degree. Do it well enough, and even some "hardcore" riders might buy one for a changeup.