The chances of BA honouring BD lifetime gold are negligible, I'm afraid, although they're higher than the chances of BA allowing you to earn lifetime status (of any type) after the merger completes using some of your years of BD*G to get you onto the path.

BA Gold is a sight more difficult to earn than BD*G, although from a standing start it became easier last November (1500 tier points instead of 600 for Silver then 1500 more for Gold).