The constitutional test for church/state separation is and will remain one of sort of like the test for pornography - one knows it when one sees it. The test was a will remain highly fact dependent, and therefore ideosyncratic. In that regard, the courts will continue to try to parse motive (here the motive by way of some rather tortured analysis was found to be secular and benign), an exercise which is typically a rather unsatisfactory point of departure in this realm.
SCOTUS won't take this case, or any other like it, I suspect, for a very long time, until there is a clearer and more profound disagreement between the circuits as to some more generalized application of law that SCOTUS can sink its teeth into. By the way, your point of view that the first amendment is limited to a proscription of the establishment of a state religion, has long since been rejected by SCOTUS, and will continue to be. That approach is a legal corpse that will not be reanimnated.
What SCOTUS will continue to wrestle with are applications where government fiscal appropriations are involved, such as with schools, government subsidies of faith based charities, and the like.
That is my take of the matter anyway.
This opinion invalid to the extent it is wrong.