The gamble is just too great, when there are alternative technolgies available (Nickel-Cadium for example). The results are not as striking, but the safest factor goes way up. Air Bus threw in the towel, and Boeing should do the same. A lithium related crash would be very damaging to Boeing. Safe is better than sorry.
It seems to me that BA tried to do too many things at the same time. I suspect they would be better off without the sword (lithium) over their head. The 787 is very efficent, and a great plane if it is flying.