Okay, I understand that you weren't actually trying to merge the two different artworks into one product, just testing the concept of combining tem. Line art and 3D might be made to work together visually if the central item was 3D and the "border" was 2D but probably not the other way around.
If you can do a 3D image like that in 14 minutes then I think you may have something. We have been talking about 3D laser engraving in another thread of Harry's as well; I'm sure you saw it. Many people have commented on the marketing isssue with 3D (finding willing customers.)
However, if you can add that kind of decoration to a wooden box or other wood item, or just sell it as a plaque, then it looks like it can be viable. Especially since your images are original and not clipart. It's when you get into the 60-minutes-plus kind of thing for a small graphic that the financials just won't work. For 60 minutes of laser time most people want $60 or $90 or maybe more depending on equipment. That usually prices a plaque or box or desk gadget out of reason. I realize that your image is a shallower image than 3D routing, but personally I like the look and would probably not attempt a deeper cut with the laser as I doubt it would result in as good an appearance. It is a bit like sandcarving - trying to create the illusion of depth without actually being very deep.
Somehow I have doubts that I could do that image in 14 minutes on my 30 watt machine - but I haven't experimented with 3D for a while.
Please keep us posted as to the feedback you get from your customers once you get a few products made up.