So, having had two half-year periods of sobriety, I'll say this: it depends.
If your recovery is "active" (i.e., it includes meditation, writing, meetings, posting), then what will happen is that your more extreme fantasies will begin to die down after a few months of sobriety. They may not go away completely, as they may have become imprinted, but it will get to the point where you could go months without having a more extreme fantasy, as I did. And yes, the vanilla stuff will turn you on again. However, if you just try to white-knuckle it, then probably not.
Also, this is a very good reason to quit using porn as soon as you can. Every time I had a hard relapse, my brain not only picked up right where I left off, but started building on top of those more extreme fantasies within days. Quitting and staying sober helps to ensure that your brain doesn't run away from you like this.
