It is probably flowing from using proportionalism as a valid means to reckon the morality of a given action. :) I know that proportionalism is a condemned ethical theory (condemned by Bl. Pope John Paul II in Veritatis Splendor), but it seems most people do not care.
Will it be followed? That's the question. How often is the Pope releasing letters et al stating certain things, like don't remove kneelers from the Church, yet, there's a lot of Catholic Churches minus kneelers.
I'm all for cultural and regional influences on the Mass, as long as there is no liturgical abuse. New Zealand parishes are rife with them. Priests and Parish boards aren't going to listen to a manual any more than they've been listening to the letters and other teachings the Pope has released.
Plus, so many of our Priests aren't teaching against "gay marriage", fornication, abortion, contraception, are we expected to beleive a manual will make sure they bless themselves in the right order?
Its a good move if it grabs attention, and if it can be properly monitored, but I can't see it working out in the Parishes where priests just want their own little Kingdom.