I have a couple of thoughts that may have been missed.
The first is about the "pressure to perform" issue, which makes me wonder if using non-penetrative play as a thing in itself might be a good way to warm things up towards more fantasy/kink related areas, without needing to put the onus on him to make big changes to his usual style. More generally, an "easy does it" approach to find what he can get into at the lighter end might help.
The second thought I had was that maybe by asking him what he fantasises about now, you're keying into the wrong sort of programmed response. Guys tend to get taught that women are defensive and even jealous about men's sexual interests, so he may be giving an answer that he's been taught is the "right" thing to please a current partner. From the bio info you give, he may not have been with many women before you (I don't know if you've talked with him about his sexual past before you became an item).
So, the suggestion I have (and I don't know if this is good advice or not) is to maybe talk about fantasies from before you got together, did he watch porn, and if so, what happened in it, did he have any particular celebrities he lusted after, or things he wanted to try, emphasise that it's about wanting to work out what he found hot, not any kind of test or competition.
Finally, I remember seeing a "formula" for having difficult conversations with your partner about these things. It goes something like, "Say there's something you've been holding back. Say you've been afraid to talk about it, and then say what you're afaraid will happen when you do. Then introduce the actual topic and the thing you need to say. Finally, ask if they have anything they want to share."
It may be helpful to lay out what your fears for his responses might be when you raise the issue or any of the suggestions made in this thread.