I think this study is being misunderstood here. Giftedness in most cases isn't something you either have or don't. Often it's a result of a better intellectually stimulating environment when growing up. Students of the same age that grew up in less stimulating environments will naturally be behind in a number of areas due to having less developed (or less extensive) neural structures in the areas of background knowledge, mental models, and other various mental procedures. In a lot of cases I believe these students can catch up, but placing them in even less stimulating environments will not accomplish this, and rather widen the gap.

Secondly and in addition, a major part of this study is about the effects various influences have on an individuals' intelligence theories and motivation -- effects of expectations, stereotypes, and also teacher behavior in class. Plenty of studies have shown how various external influences have a massive effect on a students' achievement due to the theory on intelligence they form from these influences.

So I agree giving good teachers to everybody is the solution, however there are definitely other environmental factors involved that complicate the issue. For one, breaking up students into gifted/non-gifted categories adds yet another stereotype that could potentially be harmful to both the non-gifted and gifted students.

I believe the solution would encompass having teachers that understand how these influences affect students, which will give them the capability to structure their classes and their instruction in such a way to dissipate any damage these influences can make, and instead turn them into catalysts for growth.