Motu Proprio Question

Before Vatican Council II, there were many notable examples of inculturation which were practiced by Roman Catholic priests. While they led to many profound debates about such practices, especially about the extent the liturgy could be inculturated, there was no doubt that some form of inculturation were permissible and indeed beneficial, especially when employed by missionary-priests. Jesuits were famous for such practices from India to the Americas. This meant, of course, that there was no uniform use of the Tridentine Liturgy; its practice could differ throughout the world.

Question: With the motu proprio “Summorum Pontificum’, will extraordinary liturgical celebrations be allowed to practice such inculturation, or will they be required to follow a more fixed form of the liturgy than before? Is this a good thing, a bad thing, or an indifferent thing? I know there is some room for future modification to to the common liturgical celebration in the future, but to what extent, if any, will there be flexibility in its celebration now? Would priests working with Native Americans, for example, be able to use an inculturated version of the 1962 missal, if they so wanted?