It is still unclear whether existing Dynamics 365 CE storage entitlements are ignored, when I want to use pay as you go for requests. Tried it and my entitlements dropped to a lousy 1Gb (at least in the admin capacity overview). Immediately deleted the billing policy to prevent a huge bill for something we are already paying for. You seem not to be able to choose to use the payg model only for requests and not for apps and storage. If this is true, this model will fail. Talking with engineers for weeks now. Nobody knows.