Opps yeah you are correct on the dates.
No 1080ti sales will not be hurt anyways. 1080ti is a 700 card, 1% of the performance bracket in sales, whom ever bought those cards would have bought them already. It will raise opportunity cost, but the is minor, inventory numbers won't get hurt, if they are managing their manufacturing volume vs sales volume, last I checked nV's inventory figures have been fairly stable
Steam survey disagrees with your assessment of 1080 Ti sales curve.
http://store.steampowered.com/hwsurvey/videocard/
Sales of 1080 Ti are steady over time, as compared to the massively trailed off sales of the 1080 (which only recently got a bump in sales due to the 1060 and 1070 being marked up massively due to mining)
Steam Survey DX12 GPUs:
NVIDIA GeForce GTX 1080 Ti
- April
- May
0.42% June
0.53% July
0.66% August
+0.13%
NVIDIA GeForce GTX 1080
1.65% April
1.64% May
1.70% June
1.74% July
1.98% August
+0.24%
As compared to the 1080, which was always priced at a premium before the 1080 Ti was released (and still had somewhat of a premium afterwards before the mining spiked prices of 1060 and 1070), the 1080 Ti >>is<< the value choice for GP102, which means that it's sales are guaranteed for the life of the product, as there are always people upgrading to the highest performance value product over the course of the life of such a product (Until you reach too close to the expected launch of the next generation of course).