Indie movie guy here. It will be fine. Existing pro and semi pro cameras that offer slo-mo functionality as a fringe benefit typically do so with compromised resolution (eg with a RED Scarlet you have o drop drom 4k to 2k to shhot at 60FPS and down to 1k for 120FPS, IIRC). It's a fact of life and editors are used to dealing with it, you just have to be selective about how much you use, your composition and so on. There are also ways to address shortcomings in post-processing with super-resolution plugins and so forth. 700fps at 720k is more than acceptable for many purposes (especially when you lay a breathless narrator saying 'shot with a
special camera...', because this will get used more in documentary and newsgathering than in narrative.
The more advanced frame rates will only be useful in science labs due to the increasingly poor resolution, but they'll still be useful - there was a consumer camera from Casio that did something similar at much lower resolutions but it had a fixed lens which severely limited its application. However, it became quite popular with amateur filmmakers and in high-school science labs.
I like that this is just a head that goes out to a computer. I don't think every director of photography will have one, but that some people will specialize in setting up and shooting this and then rent themselves and their gear out to productions for special effects shots etc. They'll make their target comfortably.