Also, If you're interested, ryanc43amg posted spy shots for the 2014 (!) C class here.
With all due respect to the author of the "link" write up, the GL has had the "characteristic MB vents" for as long as its been in existence. If anything, the cowl vents need to be updated so the plastic doesn't discolor and look like it's gray on a black GL. IMO at least.
After having rented Grand Cherokees and Durangos in CA(not sure how loaded new vehicles end up in National Car Rental San Fran), I have a feeling where this may be going. I hope the GL stays different enough. I really don't like the bulging rear side view of the Durango and hope this new platform doesn't dicatate too much of the body design.
We are very happy with our GL for its space and ability, but it's a Mercedes. Doesn't matter where the platform was developed and with whom, don't mess up the formula. The new ML seems to be well received but I personally think it's not my cup of tea. We'll see when the GL is presented officially, with fingers crossed; otherwise we'll have ours a while longer.