"Afghan poppy cultivation, which long provided most of the world’s heroin supply, flourished for decades due to US intervention in the country"

Wrong. The US actually paid Afghanistan $30 million to stop cultivating poppies and concentrate on other crops, but it damn near destroyed the economy, not to mention it was hardly enforceable. That's been a staple crop in the region for centuries, as is hash. The US had no more or less impact on that than did the USSR and the Brits before them.

The question now is, can the Taliban get them to grow something else that will maintain the economy? If they can, good for them. You just got rid of a huge criminal enterprise for legal crops. That'd be a win. I'm going to venture a guess that, even with the religious angle, that's not going to happen. Either farmers in the remotest areas will continue to grow it and it will impact the economy, or they won't and it'll wreck what little economy they have.