First, there are a LOT of people working on Kubernetes right now.
Second, of course it will be asymptotic for a long time. But keep in mind that we don't want or need everything that Borg has, and Borg does not have everything that Kubernetes does. Kubernetes is not a clone of Borg - it is inspired by the lessons and experiences we got by doing Borg. Often that means we learned how NOT to do something.
If we can get 75% as functional as Borg in 1/3 the time, we'll be doing pretty darn well. I think we're on track for that.