The good news: that is not happening, at least not to the full extent of the awful that I had feared.
The less good news: my period is here now.
While this could mean that I've misread my fertility signs, I really don't think this is the case. Cervical fluid, cervical position, and waking temps all pointed to ovulation on December 7.
Adding this to my other recent cycles, it's looking like I now have a very consistent 11 day luteal phase. That's not abnormal in itself, but it's a not-small shift from the very consistent 15 day luteal phase I had about 4 years ago, before I started on hormonal birth control.
I'm not concerned about the shorter luteal phase; in fact, since it lessens the duration of my PMS experience, I am all for it. I am, however, curious as to what may have caused such a substantial reduction in my luteal phase. The two factors that seem most obvious to me are time/age and HBC use, but I don't know if there's any evidence that these can actually affect luteal phases.