I am also one of the Java Lover but seeing pythons growing popularity ... just guessing the future of java
To be blunt, if you see Python as useful, and more useful than what you currently use, then learn Python.
As for me, I am one of those "old dogs" that will have to be convinced to switch (or may have to be dragged kicking and screaming ...

). For the longest time, I was TCL user, when everyone was using Perl -- eventually, giving up and switching over to Perl. If Python takes off, and Perl dies out, I may have to be forced to switch again.
As for Python and Java, I don't see how one will replace the other. Java is more than just a language. Are there any Python based application servers, web servers, etc? At least, at a commercial product level?
Henry