1. Python is definitely future proof. It is most likely going to be THE language in the near future. Machine learning and AI is most likely where most new breakthroughs will happen, and Python is well positioned to leverage this. Read more here http://blog.hackerrank.com/emerging-languages-still-overshad...
2. Python has a good standard library. It has been around for a while now, so it also has a huge number of high quality third party libraries.
3. Python is slow and this is a serious disadvantage. However writing Pythonic code is an aspect of Python that I absolutely love. I think Guido's guiding principle "code is read more often than it is written" is quite true and writing beautiful code is a thing worth learning. Other people will love you for it.