The model of creator / information-provider and facilitator has been around for a while. A specialist creates resources, a structure for learning and developing and then guides the learning, which is facilitated by someone of a lower scale, be it a less experienced teacher, HLTA, etc ... You get this in Universities with Post-grads doing some of the donkey work for the senior staff ... In sports clubs with junior and trainee coaches working under the direction and supervision of the club coach ... But the argument is that the specialists who are needed now are above the ability of the classroom teacher. It will not be cheap but the idea is that the better the resources to start with the easier it is for learning to take place. There is some evidence around this but also a lot of evidence that says the ability of the classroom teacher to engage with the learners, and to get them engaged with the subject, is more important.
We also have to remember the largest slice of any schools budget is staffing costs. Having two teachers per class (one QTS, one specialist) will be expensive. We often have these discussions here with IT. I am actively advocating a 1 device per pupil model. However in the back of my mind I know that to afford it we may have to make staffing sacrifices which may impact teaching and learning in other ways - larger class sizes and/or less TAs, more contact time, more teaching outside of specialist areas, etc.
Schools used to set a lot of things themselves. In some schools it worked, in others it didn't. That is why you get the swings from centralisation and decentralisation ... The idea is that you eventually get a workable balance. A fine idea in principle.
Ultimately I think models such as this are never a one size fits all approach and should never be mandated by central government, however attractive it might look on paper. I believe it should be the responsibility of governing body and senior leadership team to set a school curriculum and teaching practices.