BMW and MB immediately came to mind; the latter more-so than the former.
MB has created a dichotomy of its vehicles, to the point that soon the 'lesser' Benzes won't be considered "actual" MBs, but almost competing with Toyota/Honda/Nissan within the same brand name.
It's also not unlike how Buick has been retooled to be lesser than Cadillac, but greater than Chevrolet, leaving it squarely against the likes of rebadged Civics (ahem, Verano = ILX).
I think Subaru, in following market trends, has made its cars less desirable to many folks, too. However, I think that move will prove immensely successful as it doesn't have the 'luxury' brand cachet from the get-go.
But the CLA/GLA, especially as a partnered platform with Nissan, will not likely be good for the long term cachet. Sales, yes, cachet, no.
VW is likely going to be the first to dilute itself, though.