Using Pale Moon here, great browser.
FS9 isn't dead nor will it go anywhere soon. With FS2002 still hanging on, I think we will see a similar longevity to FS9. And likely longer.
Lets say you were going to introduce someone to flight sim who was hardware challenged, wasn't going to want to join the tweak fest that is FSX, has an interest in commercial flying, or all the above. You can make FS9 look great, with sweeping addons like the now free UK2000, VOZ(Australia), and NL2000(Netherlands). Also all the scenery improvements like HD water and clouds, ground textures, etc. Tons of freeware airports from FRF, Mach1DG, Gregory Putz, etc and so on. And for the time travelers like me, CalClassic, 9Dragons, and HJG.
A lot of the payware thats still available is affordable also. So flying an iFly 737 from a FlyTampa scenery to an Imaginesim scenery is quite an immersive thing. Especially with a load of WOAI traffic.
I enjoy flight sims, and will use whichever ones my PC allows me to use. No law says we have to use one. Usage of FS9 will dip over time, but I actually don't need an audience to enjoy it. I still use old games all the time that I have no idea if anyone else plays. Rogue Spear/Urban Ops, Civ 3, BF1942, MVP2005, Tiberian Sun, etc.