Airlines are pretty canny, They spend a lot of money on market research advertizing etc, If they considered repainting one of their craft in a 1970,s paint scheme would attract customers in numbers they would im sure do it.
As said i suspect the vast majority of Monarch passengers would not even notice or care one way or the other, Flying these days is a evil to be endured for the vast majority of the populace.
The days of joe public getting excited or being remotely interested about the prospect of flying are long gone.