Here in the UK the 520d is probably the best value for money F10. If you go for the basic UK spec' it comes in at almost the same cost as a 320d specced to a similar level. In fact was a few £££'s cheaper for the closest comparison specification, when I configured one a few weeks back.
Certainly will be the biggest seller here, 5-series car for sensible money and good economy.
BTW, we won't see many high specced 535i's either and even more rare, 550i's.