In 2009, Dell caught headlines with its premium Adamo slim laptop, which was considered a competitor to the MacBook Air at the time.
Yes. "at the time." And remember the Dell competitor to the iPod? There are several problems for Dell here. 1) They are a maker of commodity hardware trying to move upmarket. But the fewer units they sell, the worse their economies of scale, so how to really make something special, without having to charge too much? Apple doesn't have that problem, in part because they sell 6-8 figures of even their high-end products. 2) Sure, Slashdot readers may be an exception, but most people who want Android and Windows machines rarely want expensive ones. So most of their target market will either want a cheaper Android tablet, or, if they want to spend more, they'll get an iPad.
I think the best Dell can hope for is to be a niche player, a slightly bigger version of their subsidiary Alienware. 15 years ago, Dell and Microsoft both seemed unstoppable, but both have repeatedly stumbled since then. My, how the mighty have fallen.