I get what you're saying, but I can't think of a better objective measure for performance expectations than the manufacturers own forecasts. Otherwise, your frame of reference becomes 'what forum poster #237 feels it should've sold'.
Yeah, the manufacture would have the most authority usually.
But given the market and smartphones and how badly the 3DS started, I can't say I expected it to be doing better. It's doing all right in my opinion. 237's opinion.
The frame of reference doesn't have to be one poster though.
How about a general consensus of knowledgable consumers in the industry, with a large sample size? They would know how well a console was performing. Like...GAF.
Just software in general. The device has a low-ass attach rate of 3.something.
Well...eff.
Let's revisit this in a year or two. There's still a slight, slight possibility of must have 1st party franchies returning. Metroid, F Zero (yea....), another Star Fox, Kirby will definitely come. And the new Zelda.
That might increase rates.