I don't think the number of open tracks diminishes. But I do think we generally focus.

When one is 55 it is probably not too interest to attempt to go into the race to become and investment banker. Not because it is inherently impossible, but because there are more interesting opportunities.

Or at least: I think this narrative is the most productive, and the one I will stick to.

Depends. If one had been planning to shift tracks earlier in life but something got in the way, there would be some disappointment that the window for that track had passed.

But your narrative implicitly signals acceptance of one's station and a realistic assessment of the tracks still open which is probably the right way to go.