I don't expect to have an ARM-based PC any time soon
The ARM-related news of the time interval is of course that Apple
has announced several ARM-based Mac laptops and that early (and
preliminary) leaks are that they perform very well and are definitely
competitive. This raises the great hope in many technical people's
minds of ARM based laptops and desktops from more than Apple, ARM
PCs that would run more than Apple's
OS X macOS. This
is especially a dream for many Unix people, who already run little
or no commercial binary software and so in theory ARM support is
only a recompile away; moving away from the x86 hegemony would
please a lot of people.
(The practice of moving to ARM is somewhat different, especially for performance sensitive code. Focused use of x86 assembly is surprisingly common in various places.)
My own view is that while I wouldn't mind using a competitive ARM
based PC (either laptop or desktop), I don't expect to actually
have one any time soon. The rub is that 'competitive'. Right now,
the only ARM chip maker that can compete with the performance of
the x86 hegemony in the desktop/laptop space is Apple, and Apple's
machines only run
OS X macOS. While there are promising
developments in the server space, many of them are also bespoke to
the large cloud vendors, and also may not be particularly suitable
for scaling down to desktops and laptops (in all sorts of dimensions,
including how much money can be made on them).
Apple has demonstrated that it's possible to make ARM be competitive (on laptops, at least, although likely on desktops too), but they stand alone and I don't think it's likely for anyone else to join them. Apple has the benefit of a gigantic market for their own ARM designs that feeds a firehose of money into their R&D budget and also good assurance of large production runs even for laptop CPUs (never mind phone ones). Anyone else would be in the position of trying to take laptop and desktop CPU market share from Intel and AMD (who are already fighting each other), without the kind of money firehose and good market that Apple has.
(Apple also has the benefit of capturing all of the profit from its laptops. An ARM CPU maker would capture much less of the profit of machines with its CPUs in them; much of the overall profit would go to the system vendors or at least to the makers of other parts, like motherboards.)
The other problem is that merely being competitive isn't good enough, because there are real costs to switching to ARM (even for Unix people). It's likely that an ARM PC would need to be clearly better than the x86 equivalent before very many people became interested, and might face an extended period of doubt and proving itself. To be honest, that would be my attitude toward the first generation of ARM PCs; I would not buy immediately and let other people get those experiences.
(I think this will be easier on laptops than on desktops, because on laptops power efficiency can count for a lot. The longer battery lifetime is already one of Apple's selling points for their new ARM laptops)
PS: I would love to be wrong on this, as I'm not particularly fond of the x86 hegemony. But I'm also a pragmatist.