I'm not sure this argument works in your favour. You appear to be saying that the people who like Python 3 are those who have no experience of anything else, whereas the people who have experienced other things are reluctant to use it. You'd have to give at least a little credence to the worries of the experienced people.
The differences are small, and all the arguments against 3 are really just 'breaking changes suck' - yes, they do, but it turns out that we aren't perfect and language designs aren't perfect - you either make breaking changes or live with bad designs forever.
Python made those breaking changes - the alternative just means that in X years we'll move to an entirely different language that does things better instead of moving to Python 3, and at least having an upgrade path.
Similar phenomena are almost universally a case with new things in IT, CS and probably life. Takes older generation to "die out" for a society as a hole to accept new way.
Don't take me wrong though - I'm not trying to say experience is bad. Just saying it alone is not sufficient.