Adding an A380 to two 77W flights would double seat numbers which would not be filled instantly. Also, the A380 coming to MAN (if there would be one which I assume there will be one day) will be the larger capacity version as they do not operate F to MAN. That would mean and extra 1200+ seats per day!
I think they will probably do what they usually do. Add an A330 morning departure, then upgrade it accordingly, and if the other two flights are anything to go by - it won't be long before a third 77W will be at the so called famous EK gate at T2.