The question is where have they gone? the answer is Elsewhere, who cares , many come back, i took a few years off and am enjoying it again, for now.
As far as new players go, its never going to be a fair expectation for a newbie to start up and reasonably catch up to guys with a decades worth of flight sim experience. The games they build now are mostly pay to win, you invest in the game and you get further. Kids want it yesterday , and they drive the market. Embrace the newb, help them out, teach them, the learning curve is steep and unforgiving.
As we grow old, so does the game, i hope i get an invite to HiTecs funeral, if i outlive him, i did, afterall, help pay for it.