Currently, most of the Linux distributions are using Python 3 and Python 2 “Python 2.7” side by side in the same distribution, because many applications still requires having Python 2 libraries to run it.
However, Ubuntu is willing to purge Python 2.7 from the upcoming releases of Ubuntu 16.04 LTS default installation ISO images for desktop and server. So, you might consider this is a problem for some packages requires Python 2. But, according to an announcement by Barry Warsaw “Ubuntu developer” all applications installed by default on the ISO image are currently ported to Python 3, except Samba which is requires Python 2.7 for an application “system-config-printer” to recognize Windows printers attached through the network.
So, by default you won’t be able to detect attached Windows printers through the network, unless you install the “system-config-printer” along with the necessary packages.
Purging Python 2 will also affect the deja-dup backup application, which is not ported yet to Python 3. So, if you will consider doing a system backup you will also have to install Python 2 to be able to use it.
This process will probably affect many users by default. but you still can recall any of these packages from the official repository after the default installation.
For more information check Knocking Python 2 off the desktop iso.