Without reading through all post I’d go down the road and just write down my point of view 
On software nowadays it’s not that important to provide all new reincarnations of something already created - instead focus is on cross selling and in app purchases.
It’s not just on the gaming sector but also on office and other sectors - usually professional software gets long time support down the road and I can imagine that’s also what happens with MSFS as being some prestige project and a cloud computing demonstrator too
Some people might see the sim as “just” a simulation, but when thinking outside of this box: what if MS intends to transform this into a platform over the years coming? It could be used to improve techniques for Bing Maps and AI generated photogrammetry/cities, it can be used to create a more detailed weather forecast model which can be used on other services, it could also be used for flight and military training whenever the simulation is accurate enough to get certified by the FAA or the digital world can just be used for other Xbox Game titles like “Forza Global”
So yes, it will receive updates and improvements for a long time imho. It looks like for now more and more people come in and enjoy what we already have (otherwise servers would run better on weekends ), cross selling also seems to just work which surely will take an even bigger part down the road (third party aircraft sold through the Market Place as Local Legends/Famous Flyers). Also there likely will DLCs drop (maybe even a “CFS” module? ) as “Reno” was just the start.
Other games and sims are also running for a really long time and get regular updates, take DCS, The Sims 4, Cities Skylines, Elite Dangerous or GTA Online into account - they all somehow work in the same way as MSFS from a marketing perspective to me: bring new content/DLCs, acquire new players and sell new content to provide long term support
Heck, even Skyrim won’t die even if it’s just the refresh of the refresh of the refresh…
So, nobody exactly knows what the future brings but as MSFS now survived year two and has a good filled roadmap for next year future for now looks bright to me 