It depends on what is important to you. If you like what the current machine has to offer, go with it, but if you're really hoping for some changes that may or may not happen in the next iteration, then wait. If the new machines don't have what you want after all, then you've still got the opportunity to buy this model at a slightly lower price once the new ones are available. I've got the very model you're thinking about, described above, and I love it. This thing runs circles around my old 2012 iMac and the screen is gorgeous. The 512 GB capacity is fine for me, but I've also supplemented it with a 1 TB external SSD as well. I wanted the discrete graphics, and I also was concerned that Apple might start removing ports and I really wanted all of the ports that this rMBP has. There are times when I am using both USB ports simultaneously, for instance. I don't use an external monitor with this rMBP but wanted the option to do that in the future, which is one reason why I did not purchase another iMac instead. I made the decision to buy this machine back in December, even though I knew that there would be new models coming along eventually; in the meantime I have had the pleasure of using this machine over the past several months and will be continuing to do so, no longer concerned about the release of the next version.
