I think its safe to say that the history of original $10 Journey will prove to be much different than the current fives. Recall that we were continually getting 2002 FEL/FEK and such CBN printed notes into late 2004, and were wondering what happened to the 2003 notes which were released (printed by BABN) in 2005. Theories for this odd release were bantied around on this forum, including the likelihood of the 03 notes being stockpiled, and put at the back of the vaults where they were stored. The BOC seemed to have been in a hurry to phase them out due to the rampant counterfeiting. All these factors seemed ripe for "mix up" and the subsequent lost prefixes discovered.
The fives have been released in a far more consistent manner, and there is little likelihood that a second printer is involved in their production. There has been less bad press about their lack of security (counterfeiting) and so I'm sure every step will be more methodical. Although it would be nice to see some "lost prefixes" I'm sure a short prefix is more probable since the BOC will not want to repeat the mistakes made with the $10's withdrawal.