I think both of you may have missed the main point:
Pamela Symons, 67, said that she and her partner had lost £200 a month and were considering selling their home in Marbella.
This is not specific to one couple, but is probably a general feeling amongst many expats.
The figures talked about was "as much as £400 per month"
So most will have lost less than that, and in many cases much less than that.
So Brexit will potentially increase the pensioners returning to UK because they can no longer afford to live abroad.
That'll increase pressure on NHS, housing, etc.
I include housing because in most cases a surfeit of houses being sold will leave most of them unsold (apart from the fact that expats tend to over-value their homes) so they will be reliant on social housing when they return to UK.