One of banks' favorite cost-cutting strategies in recent years has been closing branches. But a new study suggests the approach may soon backfire. A new Bain & Company study however suggests that branch closures could actually make things worse for banks in the future. Most customers who want to do mobile banking are already doing so. And moving remaining branch customers to mobile could further imperil the cross-selling model that is already under regulatory scrutiny.

"It's a scary time for banks," said Gerard du Toit, a partner and leader of Bain's Financial Services Practice. "They run the risk of being the dumb regulated utility with all of the costs, while all the high-margin juicy stuff is hollowed out."