This paper discusses how three altering factors (migration experience, educational level and intermarriage), introducing social decompartmentalisation, appear to be connected to the language shift from the indigenous Taiwanese Kanakanavu and Saaroa languages to Bunun and/or Mandarin. The increasing intermarriage levels with the more populous Bunun people have engendered a sub-diglossic situation amidst the vernaculars where Bunun carries a higher prestige, whilst Mandarin ‘drips’ into the field formerly retained for vernaculars.