The bulk update request #11760 is pending approval.

create alias impending_anal (55) -> imminent_anal (5046)
create alias impending_oral (0) -> imminent_oral (2937)
create alias impending_vaginal (0) -> imminent_vaginal (463)

Reason: Several impending_* -> imminent_* aliases already exist, one exception being impending_doom, which is a well-established phrase in English (come to think of it, does anything else impend?).
There are currently 55 uses of impending_anal.
Granted, impending_oral has only been used a handful of times, all of which have already been manually changed over, and impending_vaginal has never been used. But I figure we might as well proactively fill all three holes at once.
There are a few other tags like impending_violence and impending_abuse, but even the imminent versions of these have much fewer uses, so I'm not sure whether it makes sense to alias them. Maybe just mass update.