My experience has been if there is a small niche, then a small company will fill it.....not one of the big boys. They are usually too busy and will eventually loose money on the deal, then discontinue the product, leaving the user stuck with useless products and scrambling to find something else that will work......this goes for just about everything: cars, medical devices, & guns and ammunition.
It's kind of a revolving door: gun shop owner doesn't want to stock guns/ammo that's not going to sell; buyer doesn't want to buy gun/ammo if it isn't available locally, ect.
Also, as someone else has said, these guns look good on paper, but are usually more gun that most folks can handle, esp. if they only shoot 'em a couple of times a year. Case in point were two fellows I met while mule deer hunting in Montana a few years ago. One had a .300 Remington Ultramag....empty case looked like a small soda bottle! He couldn't hit a 4x8' sheet of plywood at 100 yards with that gun! He finally managed to gut shoot a small buck and they found it the next day. The meat was useless, but he got to go home with a small set of antlers.
His buddy was shooting a 7mm Rem. mag....he made a nice neck shot on a buck at about 70 yards. Unfortunately, he admitted that he was shooting at the chest!
Same thing is going on with ammunition nowadays......now you have to pay top dollar for ammo that is loaded with polymer ballistic tip boat tail bullets and 'special' powder, otherwise you can't kill a whitetail.....good thing the deer in my freezer can't read the advertisements, otherwise they wouldn't know that they were kilt with a regular old flat based, soft pointed bullet!
And I don't know why ammo companies are reinventing the wheel. Case in point: the .260 Remington. My 6.5 Swede will do everything that the .260 will, so why not invest your time & efforts in promoting a cartridge that is already available, instead of bringing out a new one that most likely will fall in the obsolete rack in a few years?
Bottom line? Stick with what has been proven......