Here's my scenario. Special promo ends on a date... I have reminders set for different intervals (15min before end, 1 day before, 7 days before etc.).

A trigger like a specific date would be great. Or, at least allow me to manually run automation on all users who have installed the card (it's not ideal since the ones who install cards after this aren't assigned to this automation). But the point is that countdown reminder sequence can be initiated. You can check how it is implemented in GHL (Set event start date action that follows 'wait until time to the event start date' actions for implementation ideas).

I think it would be a very big and helpful update to your Automatic Workflow builder that many would find useful.