To solve this perceived issue, Subway is introducing self-service touchscreen kiosks in its stores and rolling out a mobile app similar to what Panera Bread debuted in mid-2014. It also plans to install digital menu boards and offer free wi-fi at some locations.

"It's really a vision and strategy in how we want to evolve," Carman Wenkoff, Subway's chief information and digital officer, told Bloomberg. "Customers are demanding a more complete experience."

Subway's woes aren't entirely customer-side, either. The company is facing stiff competition from the rest of the fast food industry which is nearly universally moving towards healthier food options (the meat monstrosity that is the Carl's Jr Baby Back Rib Burger notwithstanding), a market niche that Subway used to dominate. What's more, many fast food chains are similarly upgrading their technology offerings for customers including many of the same things Subway is: free wi-fi, digital signage, mobile apps -- McDonald's will now even deliver your order to your door.

Whatever the cause, Subway saw a 1.7 percent drop in its US sales last year, the third straight year they've done so. As a result the company has already announced that it will be closing hundreds of locations. And, according to research firm IBISWorld, 2017 looks to be more of the same.