It is inevitable guys you know it's going to happen.
It's NOT inevitable.
But I do think it will happen at some point. But keep in mind.. they have shown a willingness to add new content types that are not level based [Like GSF]... so they could very well take a new direction at any time in this regard.
The only thing inevitable about MMOs is:
1) they change over time.
2) they eventually close somewhere down the road.