In my opinion when BBI airport will open next year there will be a lot of change in Berlin airline market.
LH have intention to move BBI into a small hub like DUS with a lot of new european route and some long range route.
AB is now the number one airline in TXL and wont to maintain this position in BBI. They offer a small hub with national, european and some long range route.
The position of low cost airline especially Easyjet and Ryanair is uncertain. New BBI have major cost and low cost airline may be reduce their presence.