A new article came up in 2016 and it is a case study of a 19 year old male that goes through bone anchored palatal expansion. The technique is called MARPE (microimplant assisted rapid palatal expansion) and although it requires a surgical procedure to anchor an expander to the palate, it does not require an osteotomy (surgically splitting the maxilla at the mid-palatal suture).
This article is interesting because it completely ignores the dogma that bony change is only possible in children. It even includes a table to of recommended expansion rate based on the age of the patient. Note that this tables applies even to adults over 30 years old.
This is further proof that maxilla expansion and cheekbone widening is possible in adults