Something to consider: there hasn't been a great way to get Python 3 on RHEL / CentOS until this year. The IUS repo is an option, but it makes distributing a Python 3 package difficult: you have to get EPEL installed, then IUS, then you can finally get your own package in.

I'm happy to be able to drop Python 2 support in my projects, but I've had to hold off on some of them that run on RHEL / CentOS.