Yes, it's true that the Cedar stack supports forking web servers like unicorn, and that an individual dyno can run multiple workers and therefore serve multiple requests at the same time.

However, dumb routing is still very problematic – even if your dyno can work on two requests simultaneously it's still bad for it to get sent a third request when there are other open dynos.

Also, for apps with a large-ish memory footprint, you can't run very many workers. A heroku dyno has 512mb memory, so if your app has a 250mb footprint, then you can basically only have two workers.

Another essential point to note is that the routing between cedar and bamboo is essentially unchanged. They simply changed the type of apps you can run.