I too do not think it will come to a strike from BALPA - but not for the reasons you describe!
We are still in negotiation. BA have not imposed anything yet. BALPA's current proposal is meeting BA half way, and is based around what we believe BA can reasonably afford. I also believe that the proposal is a company wide proposal (although do not quote me on this), but it is designed to make the distribution of costs to all workgroups a little fairer. Personally, I am not that happy with the BALPA proposal from a financial loss point of view. But if BA cannot afford to pay the full pension, I cannot have it - a fact of life. You cannot make someone give you something that they do not have.
The important thing is to make the benefits returnable if affordability is no longer an issue in the future. I think this will be the sticking point as to whether a deal is accepted or not. That and the cost of upgrading benefits right now.
Any changes are due to be implemented in April. So that will be the absolute deadline for the discussions. However, I suspect it will all be agreed by the end of January. However, BA will probably make it dependent on the cabin crew not striking - but there is no way that will stop them. Most crew do not care about losing half of their pensions. For some reason, many are of the opinion that losing half of a little is not a worry. Their argument seems to be that they will not have enough anyway, so why worry if you only have half of not enough? A very strange logic to me, but there you go.