Answer to the thread question: 1) When they're significantly cheaper than physical copies, 2) AND/OR Storage, such as 2a) external HDD support and/or easily changed internal drives - providing capacity is supported > 2b) such as 3TB and above; 3) AND/OR internet bandwidth data caps are eliminated as well as ubiquitous HIGH SPEED internet.

If the above are met, then we can do DD. Otherwise, the number 1 reason or obstacle for DD not kicking off, is point 1.