I believe the computer-enhanced "spy pictures" are pretty close to the final design of the new 5-series. Think of the car as a 3-series writ large.
Hopefully, at least for the US market we'll see a 525i (2.5-liter L-6 around 175 bhp), 530i (3.0-liter L-6 around 225 bhp), 540i (4.0-liter V-8 around 290 bhp) and eventually a new M5 (supercharged 4.0-liter V-8 around 420 bhp). Unlike the current M5, the new M5 will offer as an option a variant of the M3's Sequential Manual Gearing (SMG) system, which will allow for fully-automatic operation of gear shifting. I've heard the new 5-series will have iDrive, but it will not be as complicated as the iDrive system on the new 7-series.