I imagine the emphasis will be on the short in "short term" in connection with the bmi brand. Most BA corporate customers will want the BD routes adding to their existing BA/IB/AA contracts swiftly. Executive Club members will want to earn and burn on BD routes. And BA has no history of maintaining brands of airlines it purchased (Dan-Air, Brymon etc), although of course this time it is IAG doin the buying not British Airways - but I still think BD will be rebranded fast, with "operated by bmi" in small print on aircraft noses in order to "keep bmi as a going concern" for legal/merger reasons.
Donington Hall allegedly already up for sale.
While it is sad to see an airline brand with an East Midlands history be devoured it will in the medium term secure more jobs than are lost.
I have previously received the same news about my airline employer being purchased by a European big boy at the same time of year. While we did worry things turned out ok. I hope the same applies to BD employees, especially those currently not based at Heathrow.