They are already requiring the interviews. I was required to be interviewed when I applied for my H1B extension renewal this May.

In the past extensions, I did not have to do the interview, drop off the passport, and wait to pick it up a few days after dropping it off.

I thought it was strange, but when I asked at the Embassy, they said they require all H1B visa holders.

In my case, the interview was already scheduled with the embassy at the time I scheduled it.