Forward has Schedule for later: pick a time and the forward waits with your other scheduled messages, where you can change its time or its comment, or cancel it. When its time comes it is checked again, so if you can no longer read the message or post where it is going, it is not sent and says why.
People from a partner organization in a shared channel can now save a message for later, set a reminder on it, add it to their to-dos and schedule messages there, as everyone else can. Each stays private to them and goes if they are taken out of the channel.
Todos has Filter, Sort and Clean up, a reminder you can choose while adding, and Add to Todos on a file. Your Filter and Sort follow your account to every device. A to-do’s reminder belongs to the to-do: it appears in Activity with Mark complete and Open in Todos, and ticking the to-do clears it. A list can open on your own default view, and a thread mention you read in the thread no longer stays new in Activity.