I'm afraid that is what is going th happen. When brass does start to become available, which will not be all cartridge cases at once, people will hoard it just like has happened wih primers, propellants and .22 rimfire cartridges in the recent past. There will be a few 'sitting' 1000(s) cases and many who'll still not be able to come-up with 50 or 100.Don't folks sometimes neck down 6.5 creedmoor to make the 6mm version? I couldn't find any 6mm versions so I thought I'd try to find some 6.5. As often is the situation the brass is hard to find.
These days it seems you need to buy the brass, enough for ten years use then build your rifle accordingly.