010101 I don't think there is any extension to do it, but the API is there to change it.
There's a javascript route named user.posts, one named user.discussions and then one named just user which by default has the same definition as user.posts. That definition can be changed by an extension to point to a different page and this will automatically apply to all links to the user profile inside of the single page app.
A similar change probably needs to be done in the backend to route to the correct pages, though I'm not sure core renders a single link to the user profile in the backend. Because the user profile posts/discussions aren't pre-loaded it's a bit easier. If there was pre-loading the content classes in the backend would also have to be switched.
