LH/EW is not taking over anything - and certainly the routes that touch TXL or DUS, which AB/EY need in order to fill their longhaul services, will be unaffected by any such arrangement. Similarly, LH is probably going to be less interested in serving TXL and DUS, as they generally prefer to bring customers to FRA and MUC where they can transfer onto LH mainline.

LH is basically only interested in a wet-leasing arrangement; they will NOT be buying planes/staff, but merely "renting" them [and assuming all the risk; AB will be receiving a fixed sum regardless of how well/badly these services do, for the duration of the arrangement].