While teachers value cultural and linguistic diversity, they see the benefits of speaking different languages "in the future tense," feeling it hard to specify how language differences positively impact students' learning in the present. This study explores teachers' temporal perceptions of language differences, specifically focusing on how teacher perceptions of language differences as "future assets" are intertwined with native speakerism in the present. It draws on multi-year interviews that unveil how teachers prioritise monolingualism as the norm of classroom discourse and juxtaposes teachers' accounts with an immigrant child's navigation of cultural-linguistic assets to speak Korean and English in non-school contexts. Through this, we argue that, whereas teachers see the potential benefits of speaking different languages that seek to pluralise the educational futures, they continue to hold the normative view on language differences by not being offered the epistemic tools to question "whose future" and "whose language" are imagined as the desired endpoints of language education. Approaching teachers' statements as the outcome of the limited epistemic principles of normative futurity, this study calls for disrupting the continuity of native speakerism to support culturally and linguistically diverse students through the non-linear, reparative, and multiple relations to the futures in language education.