Yes, that's a possibility of him taking her family name. However, I'm more interested in them being married and actually being a proper family in that they are wife and husband.
However, I can also seeing them being unmarried as well, I just rather hope they get married.
This is definitely a question that someone should ask Nasu-sensei but I know there are more "pressing" questions concerning the Nasuverse and what the future holds for Type-Moon.