No I don’t think you need to panic Gerry. The company wont ‘fold’ and who ever takes them on will want to maintain goodwill and future custom amongst its customer base.
In the scenarios i mentioned above, it depends who ‘takes over’ BMI who could end up taking on the programme. BA could absorb it into Exec Club before it sells on the regional operation, or it could form part of the package to the likes of Flybe.
Another option is that LH folds it into Miles and More (as just has with the Bussels Air programme) before any sale if it involves a carrier like Easyjet who don’t have a FFP.
What this does mean is there is less certainty of how and where your miles could be used. The BMI scheme is more generous on redemption, so you will get more for your miles if you use them soon. On the other hand, you might get better availability in a new scheme.
The only scenarios where you can maintain Star Alliance status is if BMI stay independent, or its scheme becomes part of Miles and More.