I don't think there's a single answer and have posited some of them earlier on this blog in both post and comments. But there's another big one that synthesizes my musings and wraps up Miller's and her national cronies' pet causes up in one neat bow: a Griswold challenge that would take out Roe and Lawrence with it.
The best take on this theory I've found so far is Shaula Evans' (Straight White Christian) Married Couples Only on BOP.com. It's the first blogpost to take on the inherent racism in this study commission's draft proposal, too.
Of course, the bill would have to pass before such a challenge could be filed and that's hardly a certainty even if its resounding defeat ought to be. Passing anything that excludes singles would be a sure sign that the whole thing was cooked up high in the combined antiqueer/antichoice hierarchy and that it would be Supremes bound with a bullet.