Lothar actually doesn't wear the fez anymore at all, it seems, as Lee Falk changed that after Fred Fredericks took over as the artist on the strip, and modernized the characters.

The important questions are:
Will Mandrake still be in tux and will Lothar still wear that snazzy little fez?
Mandrake will still look very much like he always has. Lothar will look more modern, no fez, no silly jungle/leopard skin top. He's a modern man, intelligent, wealthy and wise. He'll dress accordingly. Imagine Ving Rhames with access to some of the best tailors in Manhattan...
Well, I'll try and be strong about the 'no fez' thing, as long as Lothar is well written and still gets to toss around thugs like they were rag dolls.
I always liked him, as even back in the old days he never felt like Falk and company wrote him as stupid, more like he was just constantly baffled by 'the civilized world.'
Ving Rhames would make a good Lothat, or the guy that played Kingpin.
I'm interested in how the artist will show Mandrakes powers. Are we going to simply see the results of his powers as in the original strips, or is it going to be a whole Doctor Strange/Steve Ditko thing? Honestly, I'd LOVE to see the latter, I'm a sucker for all that.