Tags, icons, signature images, and other graphics related to user customization within online communities is only a tiny tiny TINY part of the graphic design world and scope.
If you move out into the full world of 'graphic design', you realize that it includes things like: desktop publishing (a fullsize full bleed color wall-sized calendar), for-the-web publishing (banners, graphical layouts, graphical user interfaces, clip art), billboards, packaging for pretty much anything, and more.
The world of graphic design, quite frankly, is NOT simply looking for someone who can just make good forum tags or icons and it is also not just about C4Ds, adjustment layers, and whatever else.
This isn't to say that there aren't people/groups looking for people to specialize in these areas, but on a whole, the scope of graphic design as a field and the scope of a graphic designer is much much bigger than just the world of forum tags and avatars.
Also, there's a difference between simply slapping together pre-done renders and actually doing the renders yourself.
So, my answer to your question on whether or not the world of graphic design is changing or not is: Sure it is!
But not quite in the way that people might think.
The trend in the style of forum tags and avatars/icons tends to come and go with whatever's 'cool' in popular culture and not so much as actual changes in the graphic design world on a whole itself.
The uber-small font usage in graphic design, for example, is mostly popular in forum-based communities and on fan-based websites. It is otherwise for the most part frowned upon in more mainstream graphic design because it is inaccessible (getting too small to read) and very feeling-specific. Especially for web design, super small fonts is most certainly frowned on on more commerialized sites.