Copied from a previous posting.
I suggest you take the following into consideration before making a decision: speculations, rumors, emotions, having the ability to predict the future (accurately), unbiased and educated responses to this and other related threads, possibilities, probabilities, what someone heard, the forum person who has the psychic ability to know and speak on behalf of anyone who has considered purchasing an apple product (they profusely use the word "everybody" in their posts), etc.
One thing will happen following your purchase - an upgrade - be it a bump, hardware, software, or feature. And following that upgrade, there will be another and so on.
I purchased the nMP roughly 4 months after its release. The same questions and comments appeared long before that date. As someone above posted, it depends on your requirements. Even if the purported update comes with TB3 and slew of other updated options, it won't matter to me. All of my photography and videography requirements are fulfilled with the current model. The tone of the answer will be based on the user and if their requirements are fulfilled.
Given that WWDC is around the corner, hopefully it will provide a light on what is to come. This "could" lead to a discount on current models or help you decide if (it's announced) an upgraded model is on the way.
Best of luck with your decision.