I don't think anyone thinks 16k is the real number, but what we can track very well is the rate of uptake, that is, how fast the number itself is climbing. This is a good indicator of overall want for the product since the faster the number climbs you can infer that more people are, at the very least, interested in the product.
If I am not mistaken we are climbing at a much faster rate than at this same time for the MS, and we haven't even hit the huge catalyst which is the beta release, and the reveal of the final pricings. Many people are waiting on the fence until they know how much it is going to cost and what the final design is going to look like, and, as with the MS, there will be a huge jump at that time in the rate of new reservations.
80% is likely a good solid conservative number.