The best scenario for the pro-life side is probably not a full repeal of Roe, and I think that middle ground is where Roberts will steer this. He's a fan of incrementalism and seems to have a long game view of this stuff.
They can use Casey's undue burden ruling along with the much earlier cutoffs of basically all of Europe to rule that the 15 week line Mississippi has drawn is reasonable.
In a year or two, once the lesser anger that ruling causes has died off, another case would come to them with an even earlier cutoff. That would allow them to rule the undue burden clause to be overly arbitrary (it is) and toss both Roe and Casey as irreconcilable precedents.
Then it would all be up to the individual states, as it always should have been, and the danger of Democrats immediately using 50 Senators and Kamala to kill the filibuster and pack the Court in retaliation will have passed.