The only Constitutional ruling the Supreme Court could make about abortion is that the issue belongs to the individual states under the Tenth Amendment. This is actually what should have been the original ruling in Roe vs Wade. The Court could not rule on whether or not abortion is constitutional or not because doing so would be legislating from the bench, for one, and also doing so would also be against the Tenth Amendment. This issue is one specifically that only the states themselves can legislate and has no place at the federal level.
And if the USSC determines that life begins at conception?