A more technical solution would probably do wonders for this problem - both in initial measurement and custom solutions thereafter. Even going in for a fitting won't yield you the right results, and a lot of women are just too self-conscious for one to begin with.
Human fitters are trained differently at various locations, and VS in particular doesn't seem to adequately train their employees (or maybe because most locations are in malls, working in intimates isn't exactly her career choice so she's are more lenient/awkward about it). I was grossly misfitted at a VS like many others I've met, and the girl was pretty careless about the whole thing (didn't take her time, was 100% sure she'd done it right despite telling her I wasn't quite sure - ironically citing the fact that most women are wearing the wrong size to begin with). Additionally, well-made bras that last easily run into the $60-100+ range, so a lot of women pick up the cutesy bargain-bin ones that aren't shaped well to begin with.
And depending, it can end up being a lot like jeans where sizing will vary with different brands and styles even though it shouldn't.
I can think up ways to approach the problem, but I don't see any of them being adopted.
The best technical idea that comes to mind is using a kinetic or similar device as they become more widespread to just scan the person's form and return a result.
But, I can only compare the experience to that of a man as that is my gender, I can't see myself posing nude in front of such a device to get the perfectly fitting jock strap (or male bikini, etc). I just can't imagine doing it. I have no clue if the comparison is valid, it's just as close as I can imagine personally and I just can't see myself doing it.
I don't think the pose-topless-for-a-scanner thing is ridiculous at all. You could even imagine the device being video-based, something you run on your laptop (which obviously doesn't actually upload or even record pictures of you). If you can stand topless in front of a fitter, you can stand topless in front of a device.
A less intense approach, though, would be doing a better job of statistical modeling women's breast shapes and how well different kinds of bras fit them. If you sell bras for a while and different women return different ones, you can start to build a sense of what customers' ideal fits are and refine what bra shapes and styles get sent to them. Whether that data can be accumulated fast enough to make the service useful is an open question, but it at least doesn't sound crazy.
Human fitters are trained differently at various locations, and VS in particular doesn't seem to adequately train their employees (or maybe because most locations are in malls, working in intimates isn't exactly her career choice so she's are more lenient/awkward about it). I was grossly misfitted at a VS like many others I've met, and the girl was pretty careless about the whole thing (didn't take her time, was 100% sure she'd done it right despite telling her I wasn't quite sure - ironically citing the fact that most women are wearing the wrong size to begin with). Additionally, well-made bras that last easily run into the $60-100+ range, so a lot of women pick up the cutesy bargain-bin ones that aren't shaped well to begin with.
And depending, it can end up being a lot like jeans where sizing will vary with different brands and styles even though it shouldn't.