We do plan a premium version of the Account Activity API as you’ll see from the roadmap item here, and I anticipate that it would enable additional subscriptions and / or webhooks, but cannot confirm the exact layout of the options at this time.
For now, if you go ahead and apply for the increased access, someone should be able to assess the options. My sense is that “unlimited subscriptions” is likely to be something that would fall under a future enterprise package.
