Sophos has announced the new Sophos SG (Sophos Secure Gateway) Medium Hardware Series on the website.
You can also view the new appliances on a datasheet. There are three different hardware types with slots for further use. The newer appliances are more customisable. You can connect different modules to them:
Sophos advertised the new appliances to be way faster than the older devices and competitive vendors. Here a picture from a previous post (Sophos Partner Roadshow):