In blended learning, just because a discussion happens face-to-face, doesn't mean there's no value in recording some aspect of that discussion for learners (or you) to revisit later.
Examples
Below is one way you could run a think-pair-share.
Affinity mapping involves grouping ideas in different categories. This is often quick-fire and so works really well in face-to-face sessions. But it can be even more valuable if there's a lasting artifact for learners to revisit.
Sometimes you might want to give learners the option to speak their answers, rather than type.
Another example that can keep learners moving and bring in a wee bit of energy after a long period of sitting is the continuum. After making some hypotheses, the whole class could act out the continuum.
Benefits
Having some sort of a record of face-to-face discussions within the online course allows...
A lasting artifact of learning that learners (and you) can look back at whenever you want. (also useful for revision)
A slightly more structured approach to discussions as the instructions are built into the tasks with some accountability.
Variations
Any number of normal discussion variations you'd use in class - snowball, speeddating, debate, peer teaching etc. etc.
Using a pulse for continuum or polling questions where learners might want to keep their response anonymous.
Add different tasks for different levels to allow for differentiation within a group.
Ask learners to interview one another and record audio or video.
Simply record the whole class discussion and upload into the course for even those that weren't there to enjoy and learn from.