You live a nomadic lifestyle, while worshiping a polytheistic religion, no access to any form of urban amenities in any way, in addition to belonging to a different species than the rest of us, while being houned by religious and secular authorities? lol
Chemicals don't have free will and the ability to trick, beguile, etc.. it was a stupid idea from the start and I'm tempted to dismiss it as natural selection in Thedas
No. But neither do I live in a feudal state, serving a ruler endorsed ny a supreme religion while living on gear that dragons, darkspawn, or abominations may swoop down and ruin my day.
There is no perfect analogy for a demon, and they shouldn't have brought Michel into the camp, but tete was no sign Imshael was able to escape until then. They had safety guards in place, but Michel decided to take things into his own hands, which allowed his esvape. They had some idea what they were doing, and didn't count on some day fool attacking the wars themselves. Doubtless the rest of the clan knew better.
But my point was merely that the Dalish are hardly dying out, and I fail to see why you think they'll be dead. in under a century.