It’s believed to be 5-4 with Roberts joining liberals, although
Roberts’ supports the first trimester being replaced with 15 weeks.
I saw this on the internet but I’ve been zipping around so much this morning I could not tell you where I read it.
If Roberts votes with the majority, he selects who writes the opinion. He could write an opinion that would partially preserve Roe. It’s even possible that he initially voted against the majority to see how far the opinion would go. And then he could switch sides in order to soften the opinion- affirming the Mississippi law, and retaining abortion rights as a federal right, but narrowed.