Looking from the outside in, I think I somewhat agree with wiggy.
EASA FTL's got onto the statute book because of the significant airline lobby. Airline managements across Europe are exploiting the legislative landscape to their advantage knowing it will be years before even a concerted Union lobby will "catch up" so to speak.
There certainly doesn't look like there needs to be a prohibition on swapping fleets in BA, especially when the economics of the swap make sense, but that "luxury" seems to me, just that, a "luxury".
One hopes that regardless of any dashed personal expectations (I always thought Senior SH BA pilots could pretty much generate a LH lifestyle via bidding anyway - although being a LH pilot myself, I honestly don't really understand the lure of the LH lifestyle!), BA pilots stick together, as they're a far more potent force within the industry when they stand united.