Most people tend to keep their "turnaround" talk rather nebulous. I've asked often what people are actually expecting in terms of actual numbers or percentage changes in such threads. But they make no secret in the manner they post their expectations aren't just for Mario Kart to simply get the system to manage 100K non-holiday NPDs. Talk of how it's "only" been 8 months, isn't optimism about a system going from completely horrid sales to just not particularly good sales.
This seems like a leap in logic to me, but granted we are talking about subjective personal experiences with other people. I still see some people retaining optimism but rarely do I see anyone arguing that sales will eventually become great instead of simply better. The turnaround talk is usually pretty nebulous as you said, but that's exactly my point. It contradicts your claim that people are obviously expecting something significant when, like you said, the actual specifics of what kind of turnaround they think is possible are kept vague at best. A lot of people think things will get better but I think most people are unsure of how much better it's really going to get. I don't see anything wrong with that.
It's also odd that you say being dead is hyperbolic but make it clear that you believe the console will continue to remain irrelevant. Clearly those two mean different things to you but I feel like they're one in the same. While things do look horribly grim, I object to the idea that the Wii U's fate is a foregone conclusion. I personally don't have much hope for it becoming much more than a niche product, but niche doesn't necessarily mean abject failure or irrelevance. Saying it's possible the product will be doing substantially better a year from now isn't the same thing as ignoring its bottom of the barrel sales numbers at the moment. We saw people saying something very similar when the PS3 was floundering throughout 2007 but that platform had a tremendous, hard earned revival over the course of half a decade. And don't misunderstand me here, I'm not saying the PS3 was ever completely analogous to the Wii U, but neither is the Vita or the Dreamcast. Vita for instance is suffering a very similar predicament as the Wii U globally but has a different set of advantages and disadvantages unique to the platform. The Dreamcast crashed and burned but and the fact that Wii U is doing worse in various territories merits attention but you also can't compare graphs side by side and assume Wii U will indefinitely follow that same trajectory. Nintendo has various assets at their disposal, and I strongly challenge the notion that their franchises no longer have significant selling power.
However, don't misunderstand my apparent defense of optimists as optimism of my own. I just tend to disagree with most arguments that attempt to state, without question, what will or wont happen. I'm not arguing for one way or the other, I'm arguing that there's still a lot of things that can happen in the next gen and that it's reasonable to be a bit unsure, definitively, how things will actually end up.
For the record, I think 50mil by the end of the Wii U's lifetime would require a goddamn miracle. I'm talkin angels and shit.