Yep. I had two sisters who never married or had kids. My only brother adopted 3 kids then had a daughter after 15 years of marriage. The three kids they adopted never married or had kids either. All had learning disabilities. My brother died in 1995 at the age of 51. Never got to see his daughter married, or the four kids she had. There's no big deal about my kid's last name either. Their father, my long-time ex was adopted too.
So not the end of your family line. Brothers Daughter with four kids. I count the women DNA as well not so much the name there is a bit of mixing going on regardless as it takes two and people change names all the time. :)