Very unlikely to overturn Locke; you can read Locke narrowly and say that it's only about barring the use of public funds for the training of clergy, distinguishing it on its facts (and ruling for the challengers in Carson v. Makin) rather than overturning it. That seems like the much more likely path they'll take.
Just a reminder that I was right.
The funding in Locke was intended to be used "to prepare for the ministry." Funds could be and were used for theology courses; only pursuing a "vocational religious" degree was excluded.
Locke's reasoning expressly turned on what it identified as the "historic and substantial state interest" against using "taxpayer funds to support church leaders." But as we explained at length in Espinoza, "it is clear that there is no 'historic and substantial' tradition against aiding [private religious] schools comparable to the tradition against state-supported clergy invoked by Locke." Locke cannot be read beyond its narrow focus on vocational religious degrees to generally authorize the State to exclude religious persons from the enjoyment of public benefits