It looks like the GTX 1050Ti will be released October 18th, according to this: http://wccftech.com/nvidia-geforce-gtx-1050-ti-launch-leak/
So not too far away. How would the 1050Ti with it's 4GB compare to the 1060 with 3GB? I've also read that the 3GB 1060 is weaker than the 6GB 1060 in more than just the ram decrease. So maybe the 1050Ti will be a better buy?
If WCCF's leaked tech specs are correct (and note the all-important "IF" in that statement), then you're looking at 4TFLOPs from the 1060 3GB vs 2.1 TFLOPs on the 1050ti. Now TFLOPs aren't generally a great way to compare cards, but it gives you an indication that the 1060 is like to be in a different performance tier (again, IF leaks are correct).
The 3GB 1060 is slightly cut down from the 6GB version (1152 CUDA cores vs 1280). It should be the 1050ti IMHO, or the 1060 6GB should have been called the 1060ti, but in any case, there's very close to 10% gap between them if VRAM is not an issue. But at the moment the 6GB versions start around $50 more (or 25% higher cost relative to the 3GB). In terms of the the 3GB VRAM, my guess would be that it is likely to be a bit of an issue over the next two years, and increasingly more so beyond that. It would probably require you to drop AA and a few settings in some games. But, from what we know at the moment, if the choice is 1050ti 4GB or 1060 3GB, the latter is looking like the vastly superior card.