I think that is baseless speculation. The next retina update will be significant enough to launch at an event. Besides, the retina line only received a silent very minor speed boost three months ago?People are saying how Apple shall do a silent update with the rMBP's later this month. Would they really do that, or is that all speculation?
The current retinas are great computers for today and you can get 16GB with a custom order so if you need that, it is an option.
For me the most exciting things about Haswell are the possibility of extra RAM (unlikely) and storage included in the price, and longer battery life. Right now I don't feel like my mid 2012 retina is old tech or struggling. Occasionally when I let a photoshop file blow out in size I feel the limitations of 8GB of RAM but as said before, you can get 16GB on the current models if you purchase new. The only thing that could make me regret not waiting is if they make RAM user serviceable again on the new model, and we all know that won't happen.