[*]Druid Ritual - I can already see this example being controversial. When you first talk to the Kagha, she could mention an estimate for ritual completion timeline. A very lenient estimate, measured in-game as long rests. As you long rest, they get closer to finalizing the ritual, but the player perhaps is given options to slow it down: convincing the druids that you're about to find Halsin so they should wait, stealing the Idol, etc. But if you're continually slow and don't make an effort to delay the ritual, the druids leave. The tieflings remain though, and this could potentially add content in the form of changes to the tieflings' social structure/hope/attitudes, that the player would have to navigate/resolve. Or a Minthara quest on the evil storyline to perform a ritual breaking into the Druid's secret dimension.
In my opinion, after talking to Kagha, if you long rest 7 times without stopping the ritual, then the druid's grove should be grown over with thorns and vines.
And a trail of dead tieflings should be found here and there, indicating that they had to leave and many have already been killed.
Keep it simple.
