While Wells’s evolutionary models have not stood the test of time, the three basic options he considered still hold true. We could go extinct, turn into several species or change. An added ingredient is that we have biotechnology that could greatly increase the probability of each of them.
Foreseeable future technologies such as human enhancement (making ourselves smarter, stronger or in other ways better using drugs, microchips, genetics or other technology), brain emulation (uploading our brains to computers) or artificial intelligence (AI) may produce technological forms of new species not seen in biology.
If biological humans go extinct, the most likely reason (apart from the obvious and immediate threats right now) is a lack of respect, tolerance and binding contracts with other post-human species. Maybe a reason for us to start treating our own minorities betters.