I have no problem with Arch having a "only install python3 by default" rule. They can even not distribute python2 for all I care.
But, don't make /usr/bin/python run python3, that just confuses programs which have made the (reasonable based on past experience, and official python advice) assumption that it /usr/bin/python will run python2.
On Ubuntu, "sqlite" starts sqlite2.x; if you want sqlite3.x, you must type "sqlite3". The last version of sqlite2 came out in 2005. As far as I know, hardly anyone still uses sqlite2 for anything anymore. (I could be very wrong though.) Nevertheless, people must still type that extra character "3". The sky has not yet fallen :)
It seems to me that the same approach could work for Python.
Eventually logically python 2 will be little used enough to be dropped and there may not be a python4 any time in the foreseeable future so perhaps you are just borrowing trouble.
But, don't make /usr/bin/python run python3, that just confuses programs which have made the (reasonable based on past experience, and official python advice) assumption that it /usr/bin/python will run python2.