As more and more people use internet connected devices, the number of visits to online stores will grow in 2013. Consequently (based on the assumption that conversion rates remain the same or improve) the overall amount of money taken online over the year should increase too.
Getting a site set-up and running has become increasingly easier… the number of smaller / niche retailers selling their products online will continue to grow. Nowadays you don’t need a huge technology budget to get started with e-commerce and barriers are diminishing.
The impact of increased usage of mobile devices will be evident in where retailers choose to spend their development budgets with more choosing to focus on mobile and tablet specific sites. Nearly every website has seen traffic from smart phones and tablets in 2012 and this is set to increase therefore retailers will respond to accommodate.
I don’t see that the concept of responsive design (a single site that automatically resizes and realigns itself to the specific screen resolution) will take off in 2013 for e-commerce sites, but we may see this in the more innovative ‘brochure-ware’ sites.