Some good posts here.
ENI said "Losing plot would mean people would deserting BMW for Audi in enormous numbers. But they don't. Why people buy the car? Because they like it - they like the styling, they like the ride, they like the whatever. Even if the car is not best on paper, or winner of duels."
This isn't a very accurate way to judge a current car. Frankly, M-B and BMW can release dog poop for 10 years and still sell like hotcakes. As we see, the disaster of M-B's from the mid 90's to mid 2000's has recently JUST started to hit their momentum, while they lose market share to BMW and Audi in the recent years.
The F10 could have come out any which way, and it would have accelerated sales from the E60 (not a big deal, as with population growth, etc., every new car should sell over the old car to even remain stagnant in terms of popularity during its respective time). The F10 is a great car on its own, but the reason for its popularity are credited to its forefathers more-so than it itself, namely the E39, and E60. Hell, the E60 was a stylistic disaster, but that didn't hurt its momentum. Right now BMW can do whatever they want, and they will sell, the Bangle era proved that in terms of style, and this era is proving it in terms of driving dynamics. Both have completely 180'd on enthusiasts who got into BMW for their initial reasons. Oddly and predictably enough, BMW fans are now open about how ugly the "Bangle era" cars were, and how nice the new cars are, while if BMW goes sporty and brings back controversial styling, in 8 years BMW fans will say how "boringly soft and Lexus-like" the F10 era drove, and how "boring and uninspired" it looked.
What BMW does in the next 10 years will determine how they will be perceived in 15-20 years. Right now they are the sporty choice by default, although they aren't offering the sportiest choices anymore. Public perception still paints them as the "Sportiest choice". Audi is just at the introduction level of baking in the fact that they are overtaking BMW in that. What BMW does from here on out will determine whether they can keep to their "throne" - The one that got them to the very place that could sell fugly Bangle-era designs, or supremely heavy, soft Sedans.
With the F10, I see it as unable to claim any type of victory in an absolute sense over its competitors. Instead of being "Leading" in either category (Luxury or Sport), they seem to be the least extreme, and BMW is currently "the best middle ground". It's not as quiet, reliable, logical, or comfortable as the E-Class, and it certainly doesn't drive as smoothly, and it's not as sporty and precise as the A6. It however, is sportier than the E-Class, and more luxurious/comfortable/quiet than the A6.