My daughter will be 10 when baby #2 arrives. Totally understand your question. In our case the two siblings will have at least 8 years together before the oldest leaves the nest. You will have 9 years. I think that in itself helps the bonding process. Guess we shall see

In some ways it will be nice having an older child around to help a little here and there. When my daughter found out she was going to be a big sister to a brother, she was so excited. She still tells me she won't change any "boy" diapers but she'll hold him and give him lots of kisses. It is like someone mentioned before, depends on how we raise them. Try to allow your child to be involved as much as he or she wants to help with the new baby. Don't force and the oldest will naturally be curious.
Blessings to you and your expanding family.