“Will mortgage rates remain low?” Probably, for the time being. It’s a question many homeowners, and potential home buyers, are asking. But with uncertainty rampant, thanks to turbulent financial markets and the spreading coronavirus, it’s hard to say for sure just how long they’ll stay rock bottom. Last week, for instance, the average rate on a 30-year, fixed-rate mortgage ticked up slightly to 3.36 percent from a record low — despite financial indicators that suggested it would fall.