After ninety-five years (or so) of two camps - the Turnerians and the anti-Turnerians - bashing one another, there was something of a collective sigh of relief when the controversy around the Turner Thesis was set aside. Even though it was largely unresolved. The situation was so desperate that one didn't even write the word "frontier" for a number of years for fear of being shown the door: the term had been used like a secret password among Turner supports to indicate one's allegiance, all the while attracting the ire of the "anti" camp.

There are two things to consider, as the dust has settled, about what Turner was saying. Both are macro models, and like all things macro, large models tend to fail when considering at least some specifics. That doesn't mean that macro models are bad. They can be useful in considering the large view of things. Similarly, just because some specifics challenge the validity of the macro model doesn't mean it is not useful as a construct.

So to the two things: the first was the Turnerian idea of successive phases of the development of the Frontier: Native Americans, trapper, sod busters, farmers/towns, etc.; the second is the idea that the North American frontier was a pressure valve that allowed democracy and American capitalism to thrive. The idea behind the latter was that as long as free land and Western opportunities were available on the frontier, Eastern inner city problems with wealth disparities could be resolved by having at least some of the poor moving West. Once the "Frontier" was closed in the early 1890s, the pressure value stopped functioning, and the resulting American experience shifted.

The first idea is rather mechanical. It's not a bad way to describe what happened from western Pennsylvania to eastern Nebraska and South Dakota - and that covers a lot, so it shouldn't be automatically dismissed as invalid. On the other hand, it fits less well with the Far West: California and the Intermountain Mining West was settled with far different patterns - often with nearly instantaneous urbanity (and typically west to east). So the mechanical idea of the frontier needs to be recognized as a model that can be useful, but with limitations.

The second idea is less mechanical and much larger in its scope, and it is, consequently, something that is more difficult to evaluate. I'm not sure how it was treated outside of Western studies - it would be great to hear someone address that. Oddly, this second aspect of Turner's Thesis had more relevance for the Atlantic coast (where the pressure valve had its effect) than it did for the American West (the source of the pressure valve), and yet, the debate that occurred was largely in Western historiography where it has been largely set aside there.

We need someone well versed in American economic history to tell us how Turner has been viewed since he was set aside my the late 1980s in Western studies. So what I have given you is more context than answer. Now we wait for someone to answer your question with the proper authority!