If LoTR had a post-apocalyptic setting, then I'd agree that Shannara TV series was "targeting" LoTR fans. But since video clips and interviews clearly show that the "future-OUR-Earth-post-apoc-slant" is being emphasized even more in the show than it was in the books, I think it's safe to say that LoTR fans are not the
only target audience. In fact, I rather suspect that some LoTR fans may actually be a bit turned off by the futuristic, scifi-ish slant the show is going to exhibit.
D'ya 'spose Aragorn would be caught dead in that skullcap hat and hoodie?
There's even been rumors of guns for heaven's sake!
I myself welcome the deviation from the books in that regard. It will make it more difficult for the "it's just a LoTR ripoff" purists/critics to sabotage the show before it's given a chance.
They can say it all they want about the book (the first Shannara book anyway), but the show ain't the books.