There's one or two false impressions in danger of being created here. The problem with Michael Kenna's economic model is not that he's going to struggle to make ends meet on it but that its kind of hard to replicate.
His prints start at $1000 and go up steeply with progress through an edition. Lets say he averages $2000 and gets half of that himself, or $1000. Now at that level or approximately that level how many prints does he need to sell in a year to make what we'd all call a pretty decent living? Bear in mind that he'll have travel costs and ( probably) staff costs to consider. So how many- maybe 500?
Now in each of the last several years Michael Kenna has averaged 14 solo shows in top-end galleries. He also averages about 8 joint shows and has 14 galleries representing his work, which I'd imagine means that he's available year -round there. Do you think that the sum of that might add to 500? I do. Then there's the books and the odd bit of commercial work.
So sure you can make a living as a landscape photographer- he's doing it and I have no doubt there's a few others doing just fine as well. The question is, how much of a gamble do you want to take? On the one hand there's a chance of fame and maybe fortune. On the other there's failing to cover your mortgage and health insurance. If you look at earnings in any profession you'll find there's a hugely disproportionate amount at the bottom as against the top.
So here's the thing as I see it. Either you've got the money to support yourself from other sources whilst you give it a go, or you need to keep a day job until you find out whether you're going to be Michael Kenna or (more likely) not. Either way its likely you'll have to piece together your income, large or small from a variety of sources, since as has been covered here the probability of simply swanning round the world whilst covering the costs and making a living via print sales would require a great deal of luck. For most people its a question of mixing up stock sales, print sales, the odd paid lecture, maybe some magazine articles (helps if you can write too) a few commercial jobs here and there, maybe a book, and not knowing at the beginning of a year how your income is going to pan out and what paths you're going to need to follow to be OK. For most people, they need to be pretty pragmatic and prepared to scrabble around in different areas to make things work.