When the 15" rMBP was introduced Apple quietly axed the 17" MBP many said due to poor sales. However, it did still make a profit of a few million. I think the reason for its disappearance was not wholly due to its low sales.
To produce a 15" MBP and a 15"rMBP they needed 2 production lines for the 15" instead of 1. Now they are introducing a 13" rMBP alongside the 13"MBP. Thats 4 production lines. Perhaps the low sales of the 17" meant they axed it as 5 production lines was beyond the pale.
By the next re-design (2015) it may be time for the standard MBP to go and the rMBP to take its place. This will mean only 2 production lines again instead of 4. Perhaps the 17" may return then to fanfares as if its been discovered all over again.
To produce a 15" MBP and a 15"rMBP they needed 2 production lines for the 15" instead of 1. Now they are introducing a 13" rMBP alongside the 13"MBP. Thats 4 production lines. Perhaps the low sales of the 17" meant they axed it as 5 production lines was beyond the pale.
By the next re-design (2015) it may be time for the standard MBP to go and the rMBP to take its place. This will mean only 2 production lines again instead of 4. Perhaps the 17" may return then to fanfares as if its been discovered all over again.