ad 1: Python2 will have support at least up to 2020, see http://stackoverflow.com/questions/4836375/end-of-support-for-python-2-7. Likely longer as there are tons of legacy code. In addition lots of python 3 features have meanwhile been backported to python 2. So some of the differences have vanished.

ad 2: Pascal is still living despite having lost popularity. As well is Tcl in some places, in particular if dealing with CISCO machines. If you're looking for a rock solid language that doesn't require you to rewrite programs every few years, why not trying that instead? In addition: Multi threading support in Tcl is by far more efficient than in python or perl IMHO. Runtime environment is much smaller and one can alternatively easily deploy executables without need of proper installation of runtime. And most important: you'll likely be able to read and understand your program half a year later ;-) Its just: Tcl has a strange syntax that needs getting used to, and programs are definitely longer most of the time, especially in comparison to perl's terseness.

Having to rewrite your programs can happen e.g. with java as well, especially if you are writing web applications.