TLDR: I can see where the hope comes from, I just can't get behind it with any passion unless MS come up with something very different from where they are.
The only reason anyone does anything in this space is profit, if MS were to have a realistic strategy for on-going development of win10 on other architectures (which they don't appear to) and they made it easy for partners to work with them to deliver that
on a given form factor (which they never have) then its entirely possible for that to take off and make money (which I would like but have no illusions it will happen).
However the argument that Win10M never had as many apps in it's store as others is losing (some) steam as people realise that a) most of the apps in the 'big stores' are crap and b) the ones that aren't crap are niche or games - which (in an increasingly
hypothetical scenario) MS should be able to capitalise on.
For me this isn't some despairing hope for Win10M to make a comeback just an acknowledgement that Win10 on a portable device (which I like) would be one more choice over Apple/Google both of which I've used and not liked.
Also interesting that Blackberry feel a new phone is worth a punt despite being on their knees a couple of years ago (albeit they've caved and gone Android) so Andromeda shouldn't be too much of a jump for MS *if* they want to be in the Smartphone market and
if they don't I can't see where they will remain relevant to mainstream consumers which would be a bold choice.