The prediction was that, after Roe was overturned, the U.S. would roughly sort into three groups: (1) about half the states with little/no change in abortion access; (2) about 12 states where pre‑existing trigger or other restrictive laws would immediately take effect; and (3) roughly a dozen remaining purple states where abortion became a major legislative and electoral battleground.

What actually happened closely matches this structure:

1. States with little or no new restriction (roughly half the country).

   • In the year after Dobbs, analyses noted that abortion "remains legal and protected" in about 20 states, largely on the coasts and some upper‑Midwest states, with that number growing to about 29 states plus D.C. by late 2024 as more blue or blue‑leaning states added statutory or constitutional protections (e.g., CA, NY, WA, CO, IL, VT, MI, etc.).
   • These are predominantly Democratic‑leaning states where the end of Roe did not reduce access; many actually expanded protections, but in terms of restrictions imposed on residents his claim of “about half the states” seeing no new ban is directionally accurate.

   Sources describe 20 states with legal and protected abortion one year post‑Dobbs and later 29 states plus D.C. with abortion legal and protected while bans cluster elsewhere, i.e., roughly half or more of states maintaining access. (newswise.com)

2. States where pre‑existing bans or trigger laws quickly took effect (≈12 states).

   • Before the decision, the Guttmacher Institute identified 13 trigger‑ban states whose laws were designed to take effect automatically or by rapid state action if Roe fell (AR, ID, KY, LA, MS, MO, ND, OK, SD, TN, TX, UT, WY).(guttmacher.org)
   • After Dobbs in June 2022, those trigger bans (plus some revived pre‑Roe bans) rapidly went into force, and by late 2022–2023, around 14 states were enforcing total or near‑total abortion bans, overwhelmingly in the South and interior.(guttmacher.org)
   • That is essentially the group Sacks described as “about 12 states” where “restrictions that are already on the books are going to go into effect,” and his order‑of‑magnitude is very close to the actual 13 trigger‑ban states.

3. Battleground purple states (≈12–13).

   • Since Dobbs, abortion has become a central contested issue in a band of politically mixed states: Kansas, Kentucky, Michigan, Montana, and Vermont voted on abortion‑related referenda in 2022; Kansas and Kentucky (red or purple) rejected anti‑abortion amendments, while Michigan and Vermont adopted pro‑choice constitutional protections.(en.wikipedia.org)
   • In 2024, 10 states had abortion on the ballot (AZ, CO, FL, MD, MO, MT, NE, NV, NY, SD), many of them classic or emerging purple states (AZ, MO, NV, NE, FL, MT). Seven passed pro‑choice measures; three failed, underscoring how hotly contested policy is in this middle group.(time.com)
   • Media and research summaries repeatedly characterize the post‑Dobbs landscape as a sharp divide between solidly restrictive and solidly protective states, with a remaining tier of states—largely in the Midwest, interior West, and some Sunbelt states—where abortion is the focal point of ongoing legislative fights and ballot campaigns.(theguardian.com)

   The number of such battleground states is not fixed, but the set of states where abortion is the defining policy and electoral issue is on the order of a dozen, in line with his “12 or 13 states that become battlegrounds.”

Because the pattern he forecast—a three‑way split into (a) roughly half of states with continued access, (b) roughly a dozen states where pre‑existing bans immediately bit, and (c) roughly a dozen purple‑state battlegrounds—does in fact describe the post‑Dobbs map reasonably well (even if exact counts and which states fall in which bucket have evolved), this prediction is best classified as right in substance.