I would be really keen on this feature, as well – maybe the only one I miss from the app.
I typically plan a hike or a walk with my children and/or friends following a track. Subsequently, I would be curious to see the geocaches along that route, but currently I do not have a smooth process for that. (The workaround I know of is to export the geocache waypoints and then import them into a third party app, which then of course does not update the caches later on. A bit cumbersome.)
Interestingly, the Hungarian geocaching app (Geoládák iOS, Android) can do this (but only includes caches from geocaching.hu and not from .com, unfortunately).