The 6.5-284 seems to have found a niche with long range shooters and may be more popular than the 284 ever was.
I've put together several rifles chambered for 284-based wildcats and rather like the 25-284, 6.5-284, and 338-284, but think that they are better suited for an intermediate or long action, rather than the short actions that it is typically built on,due to their COAL restrictions. The 6-284, 25-284, start running into COAL issues when using bullets longer than the cup and core 100 grain component bullets that are commonly available.
I know a marketing guy at Winchester/Olin who has told me that 284 ammo and component brass are and has been on an irregular, "seasonal", production run schedule for years due to the relatively low demand. They consider it to be a semi-obsolete cartridge, along with other low sales volume cartridges like the 22 Hornet, 218 Bee, 25-20, 25-35, 257 Roberts, 25 WSSM, etc. They employ a pull marketing scheme with existing product lines, where consumer demand dictates what they produce, and a push scheme on new products so that it is available on retailers' shelves to tempt the customer into buying it. Whenever Winchester/Olin has introduced a new cartridge, or line of cartridges, they have pushed ammo onto dealer shelves in an effort to create a demand, but once the sales of a cartridge level off or decline, they retract the variety of bullet styles and only keep those that are selling in production.
Manufacturers have very little loyalty toward customers who purchased firearms chambered for cartridges with their names on them and if projected sales don't happen, a cartridge can become an orphan before it has really has a chance to take root. Recent examples would be the SAUM line from Remington and the WSSM line from W/O.
