Our Lady said "the Dogma of the Faith," not just "faithfulness" in general. It impies right teaching by Church authorities to the population at large.
Granted, this incident is one of praxis, not dogma, but it is still "teaching" sycretism to the people of Portugal.
If Our Lady meant only that there would be a handful of people in Portugal who knew proper dogma, how is Portugal any different from the US, Rome, France, or Timbuktu?
The Remnant may be all that is left at the end, no?