I use the Slack reminder all the time, and although not perfect, it would be nice to see something like this in Asana. Not a follow up task, although there are use cases for that.
The ability for a user to click on any task, comment, project, goal, etc. and set a reminder. That reminder to show in the Reminders section under Favorites.
User should have the ability to snooze, mark complete and share or hand off with/to other users from the Reminders.
User should have the ability to set a manual reminder from Reminders as well. That is, not one tied to a task, comment, project, goal, etc.
Notification under user setting should allow for the email or browser notifications of Reminders.
User can set project Reminders that show next to Set Status.