Will I sound like a native speaker?

Short answer:
Probably not, and that’s okay.

Long answer:
Sounding like a native speaker is an extremely common goal - in one survey, 95% of clients wanted to completely change their accents. It’s also a very understandable goal. At some point, everyone gets tired of being asked where they’re from the moment they start to speak.

Unfortunately, for adults who learned English after early childhood, it's unlikely they will ever sound exactly like a native speaker, even after accent training. There is a "critical period" for acquiring native-like pronunciation, which is definitely before 12 years old and ideally before 6 years old. After that, the brain becomes less flexible in learning and producing the subtle sound patterns of a new language. This doesn’t at all mean that improvement isn’t possible, but it does mean that sounding exactly like a native speaker is not a realistic goal. If someone tries to guarantee that you will acquire a native accent, check their credentials and research their claims.

It should be noted that this “critical period” only applies to accents. Developing native-like grammar and vocabulary can happen at any point in life. In fact, there are many non-native speakers who equal or surpass native speakers in English proficiency!

The goal of accent modification isn’t to hide that you are a non-native speaker. When Australians travel to the US, it is clear to Americans that they speak a different dialect of English, but Australians don’t need to change their accents to achieve professional and personal success in America. Similarly, non-native speakers don’t need to sound like Americans. Accent modification coaching can help non-native speakers improve their intelligibility and naturalness so that they speak clearly and confidently.

References:

• Flege, J. E., Yeni-Komshian, G. H., & Liu, S. (1999). Age constraints on second-language acquisition. Journal of Memory and Language, 41(1), 78–104.

• Scovel, T. (2000). A critical review of the critical period research. Annual Review of Applied Linguistics, 20, 213–223.

• Derwing, T. M., & Munro, M. J. (2005). Second language accent and pronunciation teaching: A research-based approach. TESOL Quarterly, 39(3), 379–397.

• Derwing, T. M., & Rossiter, M. J. (2002). ESL learners’ perceptions of their pronunciation needs and strategies. System, 30(2), 155–166.