I'm no breeder, but I believe the answer is "no", there are genetic factors that you can't completely breed out. Size is just one trait in many that make up standard; a larger dog may have a beautiful coat, great bone structure, proper ear placement, and many other things that make up standard. Very few dogs are perfect, but a good breeder will produce dogs that closely fit standard. Personally, I would love to see a Yorkie that fit standard in all ways except size, and I think a 60-pound Yorkie in full coat would be gorgeous.
