So sorry to hear about your loss, I know it is devastating and not just to your wallet.
I've also read that a Blacktip needs at least 1,000 gallons and from seeing them in the wild and in tanks, it may be even more. I also know of someone from a retail place that had a large blacktip tank that they can be tough to keep. They were especially sensitive to having enough space, flow/oxygenation, and stray voltage. Not to mention the cost, 1 shark = almost your current loss unless you catch it yourself.
You could do a species only of some smaller sharks but, that isn't much for such a large tank and alot of them aren't very active, plus, I personally like the more classic "shark looking" sharks if you're going for a predator look.
Why not do something really different and creative like a really cool predator reef? You could have some lower light corals like mushrooms etc. and have several giant Pterois Volitans and other large fish. You could also go another route and do a species only with large triggers like Queen, Clown, etc. or a bunch of eels. If it were me, my inspiration would be the Shark Encounter at Sea World Orlando but, not so much for the sharks. If you haven't been, they've got a part called Dangerous Reef ( I think,it's been a few years) where they have different predator tanks like a species tank with alot of Volitans and there's also a tunnel you go through filled with these rock caves containing hundreds of huge moray eels. I don't even like eels really, too snake line, but I loved the exhibit - very impressive.
Let us know which way you decide to go. Sorry for the rambling, I guess I should go to bed, lol.