Can the Width of the Nasal Bones Change After Osteotomy/rhinoplasty?

Yes, it can move, but that is unlikely.  One of the reasons for the splint post op is to maintain reasonable pressure on the bony structure, as well as compress the soft tissue to limit swelling.  Once the nasal splint is off, the structures stabilize fairly quickly, and then gain strength out for months. 

In general, there is what we call "memory" to nasal structures that exert some influence during healing.  For example, a crooked nose tends to want to stay crooked, a nasal tip might initially appear wider than its surgically narrowed form.  In your case, the nose may want to drift back somewhat wider than was the intraop position.  The skin, muscle, and periosteum connected to your nasal bridge will support the bone, but also tend to pull it wide again.  That is increasingly true with revision cases.  So yes, there is a dynamic at play that might widen your final result.  In most cases, this is very slight, and has little to no influence on the final appearance of your nose.However discuss your concern with your physician, and he or she might make suggestions to improve the healing process. 

If the fractures were incomplete (green stick) then the bones could shift out again - pressure to push bones back in can help in those instances if suggested by your surgeon

Most rhinoplasty surgery involves removing the hump, then fracturing the nasal bones to narrow the bridge  and the nasal bones width.It takes about 3 weeks for the bones to heal. Meanwhile they can move and any trauma can shift them