After the recent EASA airworthiness directive concerning the potential for weight and balance problems with the A320neo, Lufthansa announced it would no longer sell seats on the back row of those aircraft. What are the financial implications for airlines of not being able to fill an aircraft?
Not being able to sell seats on the last row would (in Lufthansa's case) theoretically mean a 3.3% loss of revenue: LH setup for A320neo is 180 seats, 6 seats in last row.
But, only theoretically, because seat occupancy rate for Lufthansa Group was 81.4% (2018). It is very unlikely that all of the flights operated with A320neo would fly 100% fully booked. In a non fully booked flight, the last row would obviously be the first one to be left empty. The actual loss of revenue would be way less than 3.3%, but how much, it is impossible to say.
Anecdotally I'd say that it is a blessing the last row is out of service for now, this Business Traveller article will give you an idea why: no window, seats do not recline, legroom is smaller...