In case anyone lands on this thread through search, etc, I wanted to link to this new feature which somewhat addresses the initial concern I had there:
TL;DR: We’re not automatically allocating dedicated IPv4 per app on the first deployment anymore. If you’re deploying a new app that only exposes HTTP on default ports (80, 443), your app will get a shared IPv4 automatically, instead of a dedicated IPv4.
With our rise in popularity and the scarcity of IPv4 available to the world, we’ve decided to implement a way to route multiple apps via the same IPs.
By default, your app will now get a dedicated anycast IPv6 and a “shared” anycast IPv4 if it…