I would wager that a typical programmer can be highly proficient in Python in a couple weeks. Non programmer types like engineers may take a little longer but the point is that the learning curve is not steep. What structures are in place to insure the language is maintained and expanded. Its expressed purpose is the promotion of Python. During the time I've been involved with Python I have heard of few defectors while many newcomers to the language express joy in their newfound tool.
Languages do just fine without commercial marketing.
PERL and LISP come to mind. When a language is very new it needs constant attention from the author as new ideas are contributed, but once the language stabilizes around a feature set the job turns to providing libraries of modules. This is the phase Python is in. Once the syntax and feature set is largely fixed, people spend most of there time using it to get the job done. These applications and supporting modules can be provided by commercial ventures as well as freeware.