I can only speak for myself, but if the first part in a series really got me hooked, I'd want to know how it continues, regardless of the genre. Stories develop and genres sometimes shift, it's in the nature of things, so I wouldn't bet myself up too much about it. At least for me, the story always comes first. I've got to tell it as it is floating around in my head. The readers are actually at the end of the process. You have to be content with your book first. Don't bend too much just because a reader might take offense.