Yarn tries to do the same thing, but is quite different. It's skewed toward running short running jobs, like batch jobs, it was meant for hadoop and co after all.
Borg/Omega seems more like a combination of Mesos at the scheduler layer and Marathon/Kubernetes on top. It's funny to see how many services they run on top of it though.
This is exactly right. Marathon or Kubernetes running on Mesos or Mesosphere's DCOS is functionally similar to Borg.