You worry too much
WAY TOO MUCH
It did not stop me from buying a 22-454. One run of brass was made, EVER
For the past few years, many WSSM shooters stopped using those rifles, or they have opted to pay usurious prices for ammo, due to the shortage of ammo and/or component brass. Since the WSSMs are all orphaned, no manufacturer that I know of is cataloging them, and Winchester/Olin is only making "seasonal runs" of ammo, but not on a regular schedule, and, maybe, component brass, I'd opine that buying a WSSM as a "shooter", rather than as a "collector", is an "iffy" move.
That doesn't mean that I don't think that the WSSM aren't good/useful cartridges. Heck, if I did, I wouldn't have two dozen Winchester/USRA 70's chambered for the three WSSM cartridges, but most of them are NIB "collectors", not "shooters".
I don't have to worry about WSSM ammo or component brass, as I have a lot of 25 WSSM ammo and Federal 223 and 243 WSSM component brass on the shelf.