I don't think tunes are in any danger of dying, there are tons of young people playing in sessions and bands. Tunes are still being passed down between generations in informal social gatherings.

Trad songs may be a bit more precarious. It's all well and good saying they were the songs of the people, but the very act of collecting, preserving and even performing the songs seems to have become an intellectual pursuit. I'd go further and say that some (not all) of the current young performers of trad songs on the UK folk scene are a bit too precious about it. Yes, some younger traditional singers sing from the heart with real love for the songs, but others perform as though they are practitioners of an obscure art form which must be revered.
I have a feeling that, in the UK at least, trad songs will survive in PhD theses rather than in people hearts, but young people are contributing to that situation as much as older ones.