I think concerns that Shredder won't look Shredder-y are very valid. It hasn't really occurred to me until now that they will want to contextualise this the way they did Transformers, and there are things about the Turtles characters that literally make no sense against a "realistic" backdrop.
It kinda sucks, and you can definitely head in the complete opposite direction and embrace the comic bookyness by setting an appropriate tone where that stuff flies. The default in a post Nolan-Batman world, however, is definitely to try and play down the outlandish aspects to the point where it *appears* seamless with "reality".
It's really, really, really difficult to get a feel for where this movie is positioning itself, but with this style of foot clan, yeah, you're absolutely spot on expecting Shredder's appearance to revolve around something functional. Much in the same vein Nolan's Batman looks like a commando dude first, with considerably downplayed pointy ears, batman emblem and a cape.
I am by nature a pretty optimistic person, and I can even kinda extract things to enjoy from at least the first and third Transformers movies (there's like a moment or two in RoTF I like, too, but man that's a bloated mess), so I'm interested to see how this turns out.