Gwynedd council leaders have voted to consult on closing a rural primary school which has just eight pupils.
Ysgol Llanaelhaearn had 42 pupils in 2012, but is predicted to have just five pupils by 2021.
Local children would be given free transport to another school four miles away in Y Ffor.
Aled Wyn Jones, the area's county councillor, said the school's closure would be a "very sad day", warning it could hamper regeneration attempts.
A report to Gwynedd's cabinet said it cost more than three times as much to teach a pupil at Ysgol Llanaelhaearn than the county average, at £12,671 a year compared to £3,884.
Closing the school by September 2020 would save the council just over £75,000 after taking the additional transport costs into account, the report added.
Councillor Jones said he was "concerned and disappointed" by the situation, saying the school provided "a very high standard of education".
He warned it would have a long-term impact on attempts to regenerate the community, including a plan to develop social housing for 15 families.
The school has one full-time teacher with a full-time assistant, and shares a head teacher with two other schools.
Councillor Cemlyn Williams, the cabinet member for education, thanked school governors and others for their "passionate input" into finding solutions to the "critically low" numbers of pupils, but said the cabinet felt the school was not viable.
Cabinet members voted unanimously to put the closure proposal out to formal consultation, according to the Local Democracy Reporting Service.