Where does one draw a line as to when it is real or not. When sky is replaced versus colors, saturation etc are significantly worked on versus items cloned out, light painting in post etc. etc.
A broader question: is an image art or a depiction of reality ? This is where genre comes in I guess. A debate that won’t ever be resolved.
for now I am enjoying the software advances and fascinated by the possibilities.
		
		
	 
Photography is Art, though through the years there have been efforts to declare it's not art and is simply a Journalistic Documentation. But I think that's an argument that has no basis anymore. Perhaps 150 years ago it was just to document because even with film in it's most early stages was quite limited. But it wasn't long before dodging and burning and other techniques came into play where film was no longer merely documenting a moment in time.
But because photography is art, that doesn't mean for the majority of Landscape photographers that Replacing a complete Sky would still be considered part of that Art, it would now turn the photograph from Art into Digital or Graphical Art which are 2 totally different things despite obviously having some things in common.
Replacing is different then Processing. So because we process a photo, I don't believe that justifies or equates to wholesale replacing of a sky. 
The Processing of photos has been going on for over a 100 years now. And what most of us do, is no different then what we had been doing with film. Whether it's dodging and burning, or increasing the saturation or even bumping certain colors. It's nothing new. So in my  mind at least, Processing is totally different then Replacement.
Now everyone may not see it that way. And there may be some who choose to replace skies and create their art that way. We have those who do that here, and I don't know of anyone who has put them down or lessened their work. All we will ask is that you declare that the sky was replaced.
What I wonder with this is many of us dual process our Raw images, one process for the ground and one of the sky. We still need to blend these together. With the Sky Replacement tool, would it allow us to "Replace" the sky with our processed version of the sky from that image? The reason I ask is I know some people do have problems with seamlessly blending of their skies back into their images. So this could be of use to them if it offered that benefit.