2019
I've been doing some number crunching in anticipation of the two B 757s not being at BRS next summer as we've been told will be the case on this forum. It seems that BRS is to become a 4 x B737 base next summer.
If the 757s are replaced by Boeing 737-800s I estimate a loss in the region of 50,000 seats in the six months May-October. If they are replaced by Boeing 737 MAX 8s, the Wiki TUI Airways site shows these as having the same number of seats as the ordinary 737-800s so the accumulated seat loss would be the same. However, the Wiki site for Boeing 737 MAX aircraft states that the 8 can hold up to 210 seats. If this is so and TUI put in that number of seats the accumulated loss would be about 18,000 seats in the six months mentioned.
The MAX 10 which doesn't seem to be imminent with TUI and might find a TUI home or homes elsewhere anyway can, according to the Wiki 737 MAX page, hold up to 230 seats. If that came to BRS there would probably mean no loss of seats after the 757s went.
On the plus side the addition of two more 787 routes in summer 19 will add over 7,000 seats.
If the 757s are replaced by 189-seat aircraft next summer it can be seen that the loss of seats in the main summer months would be very significant, unless TUI via its own airline or third party carriers increases the number of rotations on some routes.
Looking at growth next year as a whole across all the airlines, easyJet has said they will be adding another 200,000 passengers in 2019, Ryanair has announced a decent increase for this winter which will flter into the first three months of 2019 and Thomas Cook will be offering another 12,000 seats in early spring. If there is nothing further of any significance and TUI does 'forfeit' 50,000 seats through using smaller aircraft the airport will struggle to increase passenger numbers by much more than 190,000 in 2019, a growth rate of around 2.2% for the year (based on an anticipated circa 8,650,000 for 2018). If there are no TUI seat losses, as things stand next year will do well to rise by 3% overall.
That would make the projected 10 mppa by 2021 a tough ask, unless something is in the wind not yet announced.