Reasons:
- no rumors (except two irritating benchmark leaks earlier this year)
- Apple waits for IGZO availability
- Intel had production/yield problems delivering a special over clocked Iris Pro version as Apple requested
- Intel has problems releasing Thunderbolt2 this year. I'm worried about MacPro too.
- No time! The year is pretty much over. Managing pre x-mas logistics is too tricky and/or expensive.
- Weather. Due to the heavy storm in Japan some crucial parts are probably delayed.
- Intel decided to delay the Broadwell node, marketing-wise delaying Haswell artificially will help to extend the Haswell lifecylce further.
- the infamous analyst Ming-Chi Kuo of KGI Securities is wrong, again
Even if Apple decided to hold back IGZO for future Broadwell macs, the TB2 port and o/c'ed Iris Pro iGPU are probably the two major reasons why MacBooks are delayed until February 2014. I believe Intel is to blame for the 2014 shift.
Your username is appropriate