That isn't what I've seen. The .257 Roberts is more popular now than it's been for many years. That's because the "rifle hobby guys" have kept it alive. Some of us have noticed it's very nice as is. Heck, even the .250-3000 still lives on simply because of our interest.
The 7X57 still has alot of appeal to those that appreciate classic, effective, light kicking rounds.
BTW, the .257 Roberts does just fine in a short action. E