I noticed that adding resources to my cart now causes a "Yours Forever" message to show up next to the resource in the cart. When you hover over the "info" button (the lowercased i in the circle) you get this message:
"The digital books you purchase are yours to keep. You'll always have access to them through the Logos app, even if you pause your subscription."
I don't have a subscription, so there's nothing for me to pause or cancel. It seems like Logos is already laying the backend groundwork for the Logos Pro subscription model rollout, and is assuming that most users will have one?