BR would bring in a few mainland China destinations. It's been discussed earlier that with OW + BR, dominance of the HKG-TPE market would be an issue.

There is some overlap in Northeast Asia with JL. I'm not sure though whether OW can rely on JL indefinitely.

It would make me really happy if we even got a hint from OW management that they take gaps in Asia coverage seriously. With the potential demise of JL last year, there was some talk of whether OW would continue to be viable without them. I can't think of another alliance that might not be viable if one carrier went under, except maybe DL in ST, and that's a lot less likely.