Unfortunately all the hooplah about Python 2/3 porting has created an image, reflected in your posting, which is simply not true. To a large extent Python 3 is just a superset of the functionality of Python 2.x, adding such features as keyword-only arguments and exception chaining. This is typical for Python: each new release typically includes a handful of new community-vetted syntax features. What's unique about Python 3.0 is that this one, exceptional time they allowed themselves to go back and eliminate deprecated syntax and functionality, and to tweak a few aspects of the language (namely Unicode strings) in subtle, but fundamental ways.
It's been a long, drawn-out process in part because everyone uses Unicode strings (and if you're not, you should be). Python 2.x let you be fairly lax about unicode vs. legacy/byte strings. Python 3 forces you to clean up your act and be explicit. Other than that the two languages are -basically- the same. This isn't like C vs. C++ (which share an unhealthy fetish for curly braces but are quite different under the surface), but rather more like K&R C vs ANSI C, or C++03 vs C++0x.
In other words if you're waiting for Django/SQLAlchemy/whatever to transition, don't bother. Learn Python 2.7 today, use it, love it, and transition to Python 3 only when all your dependencies have made the switch. You'll then have to change a few minor things like "raise Exception, reason" to "raise Exception(reason)", but I'm sure you'll adapt just fine.
It's been a long, drawn-out process in part because everyone uses Unicode strings (and if you're not, you should be). Python 2.x let you be fairly lax about unicode vs. legacy/byte strings. Python 3 forces you to clean up your act and be explicit. Other than that the two languages are -basically- the same. This isn't like C vs. C++ (which share an unhealthy fetish for curly braces but are quite different under the surface), but rather more like K&R C vs ANSI C, or C++03 vs C++0x.
In other words if you're waiting for Django/SQLAlchemy/whatever to transition, don't bother. Learn Python 2.7 today, use it, love it, and transition to Python 3 only when all your dependencies have made the switch. You'll then have to change a few minor things like "raise Exception, reason" to "raise Exception(reason)", but I'm sure you'll adapt just fine.