Haven't seen someone not specialize because of hand skills. Most entry into specialty programs are based on grades, rank, interest in the field, research, etc. I know what you mean though about how poor hand skills could lead to less ideal grades and subsequently a lower ranking. However, like previous posters have mentioned, most hand skills can be taught and honed with good practice. If you find yourself struggling for some reason, ask someone with good hand skills from the class above for advice/guidance.
1st year operative 1 course I was a B student in terms of prep and fills. I asked someone from the class above who was good and he sat with me for a few practice runs with tips on what worked for him. Spring semester rolls around and I got an A and became an operative course tutor as a 2nd year. "Practice does not mean perfect. Perfect practice means perfect."