I created a"Checkout and Customer Accounts Extensibility” preview enabled development store and it is using the new Thank You and Order Status pages even though they are marked "inactive". The order status link in the e-mail works correctly.
It is easy to reproduce with just "Hello Additional Scripts" in the "Checkout-> Additional Scripts" configuration. That text does NOT appear on the Thank You or Order status after placing on order on the store, but does appear when I open order status from the Order Confirmation e-mail.
Attached is a video showing the screenshots: Configuration -> screens after paying -> screen from email link (shows "Hello Additional Scripts" working)
Does anyone else have this problem?