The .257 Roberts still has a good following. That cartridge may stick around for some time to come. It has the same nostalgia behind it as the 30-30 does.

What you are seeing now is the cartridge lengths sticking to three overall lengths. There is a manufacturer push for it to save on production costs.

Those lengths are:
You have the long action which is the majority of the tried and true heavier rounds. 270, 30-06, and many others.

The short action which has the 7mm08, 308, 243, and many other calibers.

The super short action, which pretty much only has the 22-250 and 223 calibers of any huge popularity. Both of which are highly popular in my area for predator/varmint hunting. It's amazing, but there are far more options for 22-250 choices than there are for the 7mm08.