I'm mainly in greement with Aaron. Why would NV wait for AMD to launch a new graphics lineup if they're able to release their own lineup first, they can soak up all the people waiting to upgrade who can't wait for AMD, they'll be far and away the best performing cards on the market, leaving an even larger gap between them and AMD, and as 1080 sales will have wained significantly, share holders will be chomping at the bit for fresh profits after heavy R&D investment.
It's not even about making money, it's about making investors money. And when they see enormous investments made, you can be damned sure they want their pound of flesh as soon as possible.
All NV has to do is release cards that perform impressively well, with an equally impressive price tag, then if AMD produce something decent drop prices at a point when initial sales have slowed anyway. There's no way they'll release a new line of graphics cards which is 'ok'. We'll see roughly the same performance gains as each new iteration, but the prices may make yoUr eyes water, at least initially.
All waiting does is leave NV with a potential sales battle on their hands with AMD.
The 1070ti and other recently released 10 series cards are just NVs way of flogging a dead horse, bugger all development cost for yet more new product for those who haven't upgraded yet.