So essentially this is a niche to win strategy? Become the dominant player in your microcosm then continue to expand once dominance is achieved. I won't argue with this, it's not applicable to every pursuit, but solid advice on the whole.
If I understand you, I don't think that's the advice at all. I believe Newport's key point is NOT "win in a niche, use that as your base, leverage that to a wider context".
I believe the essence is this:
You're gonna hafta practice a ton anyway. So one way to decide how to focus your practice is to pick a microcosm with clear feedback, and go hard on that one type of practice. It's not about the (microcosmic) prize, it's about the focus that having a prize gives you in your preparation for the real fight, which you can get to in a few years. Thrashing during practice is as much a problem as thrashing during the fight for the thing itself.
While I think it's interesting advice, my thought is that for every opinion piece advocating laser focus, there's another opinion piece advocating dilettantism and adaptability and opportunism. It's hard to know how to add that up.
