Point of fact: apple has never had a "dominant" market position with respect to any product category except MP3 players and (very briefly) tablets. Apple will not meet its "demise" if it holds only a 50%, or 25%, or 15% share of the tablet market. They have had a much lower % of the pc market for many years and done just fine.
Let's not forget that apple makes more profit than the entire rest of the industry in some of the product categories in which it competes. They will lose some market share because they refuse to race to the bottom, but if you think that's "demise," you have a strange understanding of that term.
I'd like to know how these other companies survive especially now with Microsoft and Google getting into the hardware space. There's not much they can do other than be the least expensive option. I guess they could try and out spec each other but many of the tech sites are even admitting that something like 1080p on a smartphone is overkill. And since it seems many Android fans prefer stock Android I don't see how applying a custom skin (ala Sense or TouchWiz) will be attractive. They'll just buy a Nexus instead.