The logic of blended learning is something of a Rube Goldberg contraption: if you want rich project-based learning, then you should spend a bunch of your time, money, procurement energy, political will, and professional development resources on intelligent tutoring software. The software will make you more efficient in the classroom so that you finally free up the time that you needed for project-based learning (or math talk, or rich challenges, or peer learning, or whatever). It's kind of a strange logic. You want more meaningful student-teacher interactions? OK, step 1, sit your kids in front of a randomized worksheet problem generator.
It would be great if the online part was a no-brainer, but we seem to be hardly getting closer to that point.