Other companies stopped backfilling a while ago but doesn't mean they plan on laying people off (and you can look at 2008-2010 for reference to see that some companies didn't backfill but didn't have layoffs). Not over-growing and then shrinking through attrition is one way to rightsize a company in tougher times.
People asking VPs about layoffs in public AMAs and getting answers to the effect of "it's our responsibility to make sure that we're right-sized for the upcoming year."
Cost cutting. Move to floating desk and reduction in building space. There were few more things. But the shift to floating seats was a big indicator that serious cost cutting is happening. And everyone guessed that layoffs are next.
I am based in India. US folks would have seen different signs