MYP students have an opportunity to develop conceptual understanding they will retain in the future and to form a foundation for future learning.

When I taught in California in a French school, many of our American students left the schools after the eighth grade to fully live their American High School experience and also because they had enough of the good French education to succeed anywhere. This is no longer true. That will be  (it is already) true with the MYP.
MYP doesn't teach a different content. Maths are the same all around the world, it is THE universal language. But good conceptual understanding in Language Acquisition will actually help the students in Maths even if the concepts are different.
Concepts are going to help the students to remember during their Masters Degree what they did in MYP3 even they stopped doing Maths after IBDP. That is what will remain after they will have forgotten everything.
Again : Give a man fish, you'll feed him for a day ; show him how to catch a fish, you'll feed him for a lifetime.