What is key to realise is that through the device of bringing John, the "savage," who is a representative of our modern day life, into the the future, Huxley allows both our present world and the future dystopian world he creates in this novel to coexist. Clearly then, what this is asking us to do is to compare our own world, values and beliefs, with the new world and their values and beliefs in the future. This automatically lends itself to a debatable topic if we have to consider what is good and bad about our world, and then compare that to what is good and bad about the world that Huxley introduces us to in the future. A good topic might therefore be:
In Brave New World, John's time spent out of his reservation is used to implicitly criticise the dystopian world of the future that Huxley creates.
Such a topic would allow you to focus on both the ways in which you agree with this statement and also the ways in which we could disagree. After all, this future world has done away with war and unhappiness, which could be considered definite advantages, even though they have done this only by trading in freedom and emotions such as love.