"In which case, the lede (such as it is) will need to be revised to reflect this. Clearly not every Mexican with any European ancestry is going to be referred to as "güero" or "blanco" - and the word 'predominantly' will have to go too." 

 I do not know what the source says about that. So even if what you said is true, that not every Mexican is called blanco, etc., obviously  most or some are called that. Which is still relevant to the article. You can take out the word predominantly.