The Korean heritage language (HL) speakers exercised their "agency" to speak Korean HL, and transformed their ambivalent language experiences, caused by the contradictory ideologies of assimilation and racialization operating in the United States, into a conducive "third space" (Bhabha, 1994), where they recreated their ethnic identities "anew." Their construction of new ethnic identities was more complex than the continuum model (e.g., Jeon, 2010) because it was "dialogically" fluid in Bakhtin's (1981) notion and "dialectically" hybrid--transcending Americanness and Koreanness--and it was a "distinctive new whole" in its own existence. Also, mediated through Korean HL, they were engaged with their "possible selves" (Marcus & Nurius, 1986) as bilingual members in their future "imagined communities" (Kanno & Norton, 2003). This study contributes to the nuanced understanding of the fluid construction of the HL speakers' ethnic identities in the present and future, and emphasizes the critical role played by the HL for it.