It could be that all runways that close in magnetic heading could be affected, resulting in all sceneries being updated. The problem is that the current flight sims (excluding X-Plane) will have the old data. Flight might even have the old data.
Yes, but the fact the sim use data which was current when the sim was published, it's exactly what prevents the scenery to change, since the magnetic variation database in Flight sim is static.
You might not have the most current real-world situation, but at least you won't get strange problems in navigation, as long you keep using the scenery which comes with the sim.
The issues starts to surface if you use AIRAC updates, for example for you FMC, because at a certain point runways will not match the scenery anymore, and so will all the headings expressed in magnetic courses, like airways or VOR tracks.
In an ideal world, if you start to apply updates, you should update *everything*, navigation databases, navaids and approaches in the sceneries, all the navaids in all .BGL, and of course the charts used. Everything should be ideally taken from the same source, which might be very difficult to do, especially if you have sceneries coming from many developers, which can even include conflicting data. I find it's way easier, instead, to not update anything, and stick with the data the sim came with.
