I like the profile of the new A8, wish I could afford one (with a driver)
As for modern mass-production classics, I'd probably not include the E39 M5 - recirculating ball steering, plus they flogged a ton of M-sport 5ers in that generation that made them look 85% like an M5, in foreign markets it's common to see 525i's done up to look like M5's because all they had to do was change the crossbar in the bumper for the mesh (was a separate piece) and change the diffuser to a double-outlet, plus M5 mirrors. Exclusivity kinda hurting there. E34 M5? so classic.
The E46 M3, yes. Total classic. Would need to be on the 19"s and be absolutely mint, but a car worth having in 20 years. Exclusive body, the right motor/driveline combination, stellar reputation.
We've already talked about the others, Z8, etc. There is almost nothing that Mercedes has made in the past 20-25 years that is worth labeling a classic. Likewise, Audi hasn't either - in 10-15 years time you'd look at something like an RS4 Avant and say 'that was a cool car back then, but this person must be very quirky to want to drive one now' - which is what I think when I see RS2's and ur-Quattros go by randomly (thanks Japan, and your esoteric car tastes) Porsche hasn't really made much since the 993 that is insta-classic.
The Quattroporte will be a classic amongst car people at least, I think. Great looks, Ferrari pedigree, way underpriced for what it was. The 4.7 GTS in black/black will be pretty immortal, but even the base automatika pre-facelift has an air of taste about it.
LP640 and the Aventador, probably nearing insta-classic status.
It was so much easier to name the modern insta-classics about 15 years ago....