That's bizarre. 2 and 3 are different languages, that conveniently are very similar.
Do you avoid Ruby and Perl because each other exist?
Avoid JS because jQuery and mootools both exist?
Do you avoid Ruby and Perl because each other exist?
Avoid JS because jQuery and mootools both exist?
tl;dr: I don't think the Python2/3 : jQuery/mootools analogy is that fitting.
On the other hand, I still happily use Python(2) for some things, but that is primarily because of familiarity and awesome tools like what was mentioned in the article (namely Theano and pandas). Once the Rust language becomes more stable, I hope to move most of my development to that.
Your analogy breaks on a number of levels.
And I believe Python 2.7 still receives security updates when needed.
Obviously this depends on what libraries are useful to you, but of the common libraries that people talk about, most of them do support Python 3. Numpy, matplotlib, Django & PyQt, for example, all do.
But Python 2.x IS frozen at 2.7 because of 3.