As I mentioned in this post, the only known example of the cancellation of an online version that one can draw an inference from, AFAIK, is Microsoft Flight:
- Officially released on February 29, 2012.
- Cancelled on July 25, 2012.
- Closure of the in-game Microsoft Flight Xbox PC Marketplace on August 22, 2013.
- Multiplayer servers were shut down on October 14, 2014.
So I’d expect a similar 1-2 year grace period between any announcement that development / support was to end for MSFS 2020 and / or 2024 and the inability for users to activate the product or access the on-line assets. I suppose it is conceivable just to stop development and continue to allow users to access to the authentication and assets infrastructure indefinitely, but I think that is unlikely.
I’m not expecting to see this happen any time soon, but then I did not foresee the demise of ACES studios or MS Flight either! 
I’m more concerned about the current issues w.r.t. AI datacenters consuming the bulk of hardware (CPU / GPU/ VRAM) that is contributing to their astronomical prices increases, and the media reports suggesting that this will continue for the next few years.
This must be influencing - and IMO probably restricting - the ideas and plans Jorg, Seb & Martial are considering not only for new designs & features for future versions, but also what might be included in the SUs planned for 2027 & 2028.
Based on the many comments on the official forums, many hardware configurations - be it PC, Xbox or PS - appear to have difficulty running 2024 at the higher graphical levels with acceptable performance, and if the majority of users are unable to afford to upgrade their hardware in the foreseeable future, then that really constricts the options that the executive team can consider for new features. Designing MSFS 20xx to run on platforms that market research indicates that only, say, 10% of the userbase can afford is probably not a viable financial / business decision.
Which is why, in answer to the OPs question:
I think it is more likely that the next version of MSFS -if it is to be released in the next 3-4 years - will be more along the lines of the FSX acceleration pack that extended the existing core architecture, rather than a major architectural re-write of 2024 that requires a major revision to the current SDK.
Jorg mentioned in a previous development livestream of how the original MSFS could be played on multiple platforms, so I would not be surprised to see the platform support to be continued to be extended in that area.
Perhaps, in order to reduce the demands on CPU, GPU & RAM, they could make changes that required a greater reliance on streaming, perhaps with some pre-rendering or computation done on the server side (though this is, admittedly, rather pie-in-sky thinking on my part).
Finally, I’m not sure at this point that the executive team can provide a roadmap for 2027 or 2028 - any plans that might have been made earlier this year as part of fiscal year 2027 (or 2028) planning are likely being revisited in light of the cost-of-hardware issues being experienced across the industry.