The problem with this is it ignored most of OT prophecy and makes romans 11 pretty much meaningless
romans 9 is answering the question, did God make a mistake choosing Isreal, he point by point refutes the thought israel had that they were saved by being jews, and their argument that they were chosen because they were so righteous.
He spends time after this proving that gentiles would be called Gods people
then spends romans 11 telling gentiles not to make the same mistake Isreal made thinking they were so special, because just as they lost, you to will lose in fact, god is not done with Isreal, they will all be saved at a point in time, when their redeemer comes and they repent,
romans 9 is answering the question, did God make a mistake choosing Isreal, he point by point refutes the thought israel had that they were saved by being jews, and their argument that they were chosen because they were so righteous.
He spends time after this proving that gentiles would be called Gods people
then spends romans 11 telling gentiles not to make the same mistake Isreal made thinking they were so special, because just as they lost, you to will lose in fact, god is not done with Isreal, they will all be saved at a point in time, when their redeemer comes and they repent,
It shows who is being talked about in OT prophecy.
It isn't the children of the flesh who the promises were made to.
It is the children of God who the promises are for.