Okay, so obviously I'm on record with pretty strong opinions on what genre is BEST for porn games. Fundamentally, I do think that "ludic mechanical complexity" and "sexual pleasure as derived from pornography" are mutually exclusive. Oil and water.
That said! I don't necessarily mind seeing attempts to prove this wrong, doomed though they might be. It's a very difficult design problem, and even unsuccessful attempts at solving difficult problems can be interesting and educational.
Which is why I'd really hesitate to call any genre truly "impossible" to be pornified. For one thing, you can just, like, PUT porn in anything. It's trivial to make a bog-standard first-person shooter and then put little pornographic VN segments or animations in between levels. Boom, done. The actual CHALLENGING thing, the thing that would genuinely IMPRESS me (and that I genuinely have yet to see in any genre outside of visual novels) is a game that functions well within its chosen genre AND maintains a throughline of being sexually exciting.
So, like, a pornographic spaceflight sim? A pornographic 4X empire-builder? A pornographic meditative chore simulator? All of those represent pretty significant challenges, but I can't necessarily say I wouldn't enjoy seeing someone take a swing at solving them in a satisfying fashion!