

Normal but not always. Here are some times when the skew didn't flatten back to 2007.Index or ETF vol is made of 2 components - single stock vol and implied correlation between the single stocks.
When vol increases, Implied correlation (IC) increases. Since IC is capped at 1, skew will flatten as we approach that number on the downside and IC will increase on the upside as well (all stocks rally in a "relief" rally).
Its normal that we are seeing skew flatten