Will it work?
Question: I am writing a new adult book, but it has magic in it because it is a fantasy/fiction novel. Will readers like the novel because it has magic in it or no? Answer:
Go to the fantasy section of any large bookstore. You will find plenty of books for adults that feature magic.
Perhaps you've been listening to people who look down their nose at stories involving magic as if they were only for children? Unfortunately, there are people who, if they don't like a genre and perhaps have never read it, feel inclined to insult those who do.
This is why romance novels (the most popular genre) are referred to dismissively by some as "bodice rippers." Adventure stories are sneered at by the literary crowd. Comic books, which have become very sophisticated and literary over the past 30 years are still regarded as puerile by many.
Truthfully, it's not the genre or it's particular tropes (such as magic) that determine the sophistication of a story, but how it is written -- how authentic the characters and the story world are, the author's style and voice, how complex the thematic argument, how original the concept, plot etc.
Of course, you can never please everyone, nor should you try to. You simply need to please a niche readership -- which in your case is adult fantasy readers. There are quite a lot of them (witness the popularity of the Game of Thrones
series, for example). As for those adults who don't like fantasy, they aren't your readership and you shouldn't worry about pleasing them.