You don't really know how it's going to taste until you get a fully fermented sample. All the hop aspects of the beer--bitterness, flavor, aroma--will fade with time. No idea how rosemary ages, though.
The simplest thing is to dilute it by blending with another beer, as you suggest. I would not recommend adding anything (the double dry hop suggestion) at this point. You can't undo that in case it goes wrong, and it's unlikely that doing more will solve a problem that basically stems (pun intended) from too much stuff in the first place.