This was posted in the "Use Mileage -> Star Alliance" section:

• Potential Cancellations: Even if your booking and ticketing are confirmed, if your actual travel date falls on or after the official integration date with Korean Air, boarding may be denied or reservations cancelled due to changes in alliance membership and operating carrier policies.

Quite concerning that we could book a reward ticket but it may still get cancelled if it fals after the integration date with Korean Air.