Basil
That depends on the T&Cs - as you no doubt know, many airlines allow C, J or F pax to no show without penalty, because they are premium customers.
If a C or J or F no shows and re-books, it makes commercial sense to permit this, but Y, M etc pax do not enjoy the same amount of latitude (or loco.)
This move will probably benefit the full service airlines, n'est-ce pas????