I'm looking into the impact of moving from classic to Lightning Experience and one item that I came across (which will impact us regardless of whether we move or not) is the shift from Attachments to Salesforce Files.  

We have a number of Email-to-Cases setup and I was wondering if email attachments will continue to be placed in the Attachments or will they move to Files when the switch off occurs?  I've had a reasonable hunt around the documentation and the web and couldn't find it mentioned anywhere.