Mapping is key in a lot of enterprise, and data is usually located in different platforms. That's being said, integration between those systems is essential. Of course, ArcGIS is good to manage those mapping data, but on the other hand, Salesforce is good to manage relations with your customer.
It will be very interesting to have an Add-On which help to integrate ArcGIS maps to Salesforce (embed private/organization maps, retrieve data from ArcGIS Online and plot them on a map in Salesforce, etc.).