Earlier quoted context omitted.
It's less about where Python 2.7 is going and more about where the libraries themselves are going. If you use a library which is considered deprecated by a large part of the python community, don't be surprised not to aspire new contributors. No one expects 2.7 to go away, that doesn't mean contributors want to deal with Python 2 when 3 is available elsewhere.
I can't fault PayPal for releasing their code as open source. It's great. More companies should do it. But indeed, I don't think it would be a good idea to wholeheartedly adopt their stack. gevent wasn't even a good idea on Python 2, and I suspect the large companies that use it have built up an armor of best practices and workarounds for its glitches, which you won't know about if you start using it.
In fact the earliness of SuPPort's release serves to illustrate that the primary goal: demonstrating many best practices for building servers and clients, in any language or stack. As far as gevent goes, well, that's mostly an ecosystem-dependent turn of fate that continues to serve us well. A data point gladly share, but not the core message per se. :)