The indigenous people of Mexico face numerous problems, but lacking Spanish skills is not one of those problems. These people, descendants of the indigenous people of what is now Mexico, like the Maya and the Aztec people, have been facing big problems ever since the Europeans came to their land and conquered it.
They have been segregated, forced to marry Europeans, thus their blood lineages got mixed, so only little populations remained unaffected. Also, they are having problems with communication between one another, especially because they live in separate areas hundreds of km away. Large portion of them live in isolation, in the most remote parts of the country, mostly in the tropical jungle, where they rarely have contact with the other people in the country. When they do have contact, they face another problem, multiculturalism. The Mexicans want to incorporate them into the societies, and allowing them to preserve their culture and language, but the problem is that they will constantly be exposed to other culture, and that would gradually lead to decline and dying out of the indigenous cultures.