You can choose 'Later' on the Quick Reply menu to mark the text as unread. I propose the idea of 'Snooze' - the message is marked as read and remains read until a predetermined date/time or time length (eg. tomorrow at 6 or 20 mins from now), after which a new notification pops up.

This feature would be similar in nature to Google Inbox's snooze, which I find myself using very often.

To take this feature a step further, linking a calendar event with the snooze time would be neat. Eg. if you snooze Jim's message to tomorrow at 8, a calendar event is created called "Text Jim"