I wish vendors would call time on FSX. We now have a plethora of platforms. Surely it would be better to concentrate on the leading modern sims? 
Sure, we could all make better and more reliable products, if we could afford to exploit new capabilities offered by the newer sim.
Take GSX human animations: when GSX was initially released in 2012, nobody ever seen something like that but today, with the availability of new easier to use tools, like Fuse or Mixamo or the Autodesk character generator, we could do much better. However, FSX has an hard-coded limitation of maximum 22 bones on a skeleton, which force us to compromise on realism, for example by getting rid of all fingers.
Prepar3D allows up to 128 bones (max 64 of them connected together), which is WAY better, and would allow greater fidelity in human movement, but if we tried to support both, it would mean twice the workload, on one of the hardest things you can ever do (realistic human animations), JUST to support the lesser platform.
Prepar3D has an entirely new Simobjects API, allowing developers to ever rewrite the physic and behavior of objects, and creating entirely new classes for them. Instead of a generic ground vehicles , we could define a specific Pushback truck class, possibly with real steering (pushback trucks can do 4-wheel steering, and even opposite 4-wheels steering, on request ), so they would behave more realistic.
This, without even discussing the PDK (another API which is more low-level than Simconnect and WAY faster) which has been greatly improved in V4, which allows to do very easily things that were very hard, like drawing lines/objects/shapes inside the 3d world, with no hacks.
The list goes on, and on, and on.
It's very important, for the benefits of all the community, that user understand this, and switch away from FSX for good. Would this mean you might have to say goodbye to an add-on that won't be ported, for any reason ? Possibly, but I wouldn't worry much: if an add-on was good, and there's no immediate replacement for it, something else will see the business opportunity, and replace it if there's enough demand.
