My observation is that, generally, the old CT fans aren't that impressed with MGT. The people who currently play CT don't seem to be MGT fans. (Of course, there are a couple of exceptions, as there alwasy is.)
Those Traveller players playing other additions of Traveller seem to like MGT and are migrating that way.
If you were looking at a pie chart that represented the entire Traveller playing population, my observation is that the largest wedge (the CT wedge) is staying approximately the same size while the smaller pie pieces are filling in the MGT wedge.
Given the sales of the Traveller Core Book overall and the known fact that people who post on these message boards reflect only a SMALL percentage of the people who actually play an RPG, I would say that you have no basis for making this statement.
Allen