I'm surprised neither Coutinho or Suarez have EU passports yet. They've been there long enough.
Netherlands, Italy and the UK don't have the same law as Spain where people from Ibero-America as of today, are eligible for nationality after two or three years. Then the process itself takes up to a year after you apply.
Neymar is due to get his Spanish citizenship this September. If Suarez doesn't have it yet (possibly through his wife), then I think he'll get it soon too.
To apply for British nationality, you have to be a resident for five years and fulfill the language and other specific criteria for it. Same for Dutch nationality. Suarez could have applied for Dutch Nationality had he stayed there for another year, but left for Liverpool in 2011.