Found this little nice read on the Dremel Electric razor blade sharpener... Apparently it's what started the Dremel company. Back in the mid 1930s, Albert J. Dremel and his newly formed Dremel Company were in desperate need of a new product. He had started the company in 1932 to manufacture electric razor blade sharpeners — a design he invented. The devices were a money-saving hit with consumers. But, it didn’t take long for the competition to wise up: razor blade manufacturers slashed their prices in half and swiftly took Dremel’s customer base with them. The disposable razor blade was born. And, as Dremel’s corporate history explains it, the loss brought Albert and the young company “to its knees.” Source: https://www.woodworkersjournal.com/dremel-rotary-tools-razors-edge-cutting-edge/
Depends on which you are talking about. The artist club? No, those aren't tenuous. The SE blades for Feather's copy of the Valet razor? (It’s a very rare razor, btw). Very much so. No one else makes the blade, and aside from vintage Valet users and One Blade razor users the market for those blades is non-existant. They could end production at any time, if they already haven't. They could have a stockpile of say, 5 million NOS blades, how many decades would you think that stockpile would last?