Worry is an interesting choice of words.
I think even the most stoic of traditional publishers is seeing that the brick and mortar/direct market model has lead to a shrinking demographic. Which is fine if you're just running an IP farm, but not so great when reporting to stockholders.
Look at DC's Evergreen projects, there's a clear understanding that they need to get their books as staples in bookstores/libraries to increase their readership circles.
These companies are not going to stay out of the webcomic game just because of early diminished returns. They're just working out HOW to engage the market.