This question is one that should equally well be asked of conventional agriculture – as well as of organic products – and is impossible to answer in any context about the future.
There is no reason at all for believing that GM crops will be any more dangerous that other crops, especially as the nature of the genetic change can be defined with a precision impossible for crops from conventional breeding.
It is also important to remember that GM plants are being developed for many other applications apart from food. One of these is for medicines and vaccines. New GM plants are being developed right now to enable production of enough vaccines for use throughout the world; plants also offer a unique opportunity to make medicines that cannot be made by any other means and to do so cheaply. The first example of this was a vaccine against hepatitis which is currently under trial. There are other examples in the pipeline, such as for treatment of cancer, AIDS and tooth decay.
John Roach (February 15, 2005) . Potato Vaccine for Hepatitis B: Syringes off the Menu? National Geographic News (http://news.nationalgeographic.com/news/2005/02/0215_050215_potato.html)