I'm also not sure that mass emigration should be seen as an existential threat. Many developing economies have very successfully leveraged emigration and remittances as an engine of economic growth. If Bhutan can modernise into a more open economy, those young people could start returning home with the skills, experience and capital to do great things.
https://data.worldbank.org/indicator/NY.GDP.PCAP.CD?location...
https://www.nsb.gov.bt/wp-content/uploads/dlm_uploads/2023/1...
https://www.worldbank.org/en/news/feature/2024/03/11/a-stron...