Even though I still use my 950XL and not interested in switching it over to another OS any time soon (not till the unlikely will happen that Windows for mobile is officially terminated).
Apps were only the way to get services etc to mobile devices i.e. Apple and Android from my understanding in the beginning had horrible browser capability - hence the birth of mobile apps.
Windows however has a pretty damn good browser experience (still developing some would say), and I've found that quite a number of services that either had a Windows app or have never had one work quite well via their web presence using Edge and placing web shortcuts on the start screen. I don't believe apps are the be all, end all of mobile tech. Perhaps in the past it may have been but why invest majorly in web technologies and apps for various OS' when web tech is as good if not better natively on the mobile device.
I'm keen to see a flagship come either from MS or an OEM (similar to Apple's business structure), or a number of OEMs with different pricepoint devices as I believe there is a market that would allow for both with the right marketing. A flagship from Microsoft for the enthusiast/fan and other niche OEM builds for other markets (entrylevel enterprise, etc).
Thing that HAS to happen though is to incentivise these to the carriers at least comparable to that Apple and Android offer. I know my experience with the Australian carrier, Telstra (supposedly a Microsoft partner), was very off-putting, as several times I went into these stores to specifically buy a Lumia (at the time), of various models, and each time I was steered toward (almost muscled toward) Apple or Android devices. And it occurred with other friends that decided to take up a Lumia only to be talked into another brand. This is not unique to this carrier, as I've seen countless times on forums and articles of similar stories.
Lastly each of these devices MUST be universally useable in the majority of countries and carriers (NO exclusives for a carrier any longer, what a joke). The point of growing a userbase is not to direct them to this or that carrier alone but to give users a choice and allow the carriers to be successful on their own performance, not what devices they offer.
An added point for free, I'd like to see the OS not hold back on features and capabilities. I would like to see more customisations and of course get rid of the lag with the phone when it comes to screen refreshing and app tile refresh. One frustrating thing I find with the latest build is Glance time display isn't precise, and shows incorrectly as does live tiles that do not refresh correctly. And of course, if we are meant to have apps such as Facebook and Messenger there HAS to be a way to have these open faster, refresh better and show correct updates on the live tiles.
Everything else such as OS feel and direction the ecosystem, longevity of OS lifecycle, OTA updates that are carrier independent are all good as I see it.
Rant and ramble off.