So, the use case for Heroku is straightforward: you have a webapp that you need to get online. You signup, do a 'git push heroku master' and your application is online.
Say instead that you are Yelp, you have a couple hundred developers all of whom are clamouring for the same ease of deployment that they can get with Heroku but that's not appropriate for a whole bunch of reasons (lots of internal apps for accounting or credit stuff, a custom HR app, who knows) and at Yelp's scale it is cost effective to start having devops/sysadmin type people on staff instead of just rolling that into your Heroku costs.
So the answer is that you use something like this deployed to your own hardware in house, or you use Deis or Convox or some other Docker solution to deploy to AWS or a bunch of Virtual Private Servers or something. This gives you a good management and deploy experience at a fraction of the cost (not counting that you have to buy your own hardware and also pay a competent Devops person $100k+ a year).
The way I read it, this is an example of something that works at scale for people to base their own system on. While it doesn't provide the solution it points people in the right direction, allowing them to set up something similar that works for them without having to re-do the lion's share of the work to get to that point
"devs" being the people that set up this new system (I'd imagine it'd be ops, but there's some dev work to be done to make this work)
"internal developers" being the people that use the system for the things they're working on when the new system is set up (possibly the same people as devs)
Say instead that you are Yelp, you have a couple hundred developers all of whom are clamouring for the same ease of deployment that they can get with Heroku but that's not appropriate for a whole bunch of reasons (lots of internal apps for accounting or credit stuff, a custom HR app, who knows) and at Yelp's scale it is cost effective to start having devops/sysadmin type people on staff instead of just rolling that into your Heroku costs.
So the answer is that you use something like this deployed to your own hardware in house, or you use Deis or Convox or some other Docker solution to deploy to AWS or a bunch of Virtual Private Servers or something. This gives you a good management and deploy experience at a fraction of the cost (not counting that you have to buy your own hardware and also pay a competent Devops person $100k+ a year).