The 1070 should be more than capable of 1080p/144Hz, but check benchmarks for your specific games. A 1080 would absolutely rock at 1080p/144Hz no questions, and it would probably give you enough oomph to last for years at that framerate/resolution. Personally, I'm not sure a 970--->1070 is a big enough upgrade to make; I wouldn't do it with my money, but since it's not my money, it's obviously up to you. And, 1070s are so close to 1080 prices these days, it's hard to not justify the extra $50-$100 to get the 1080.
So, basically, either GPU would probably handle 1080p/144Hz without issue, but a 1080 is a relatively small cost increase that it might be worth grabbing it for the longevity.
I see no reason to wait for the next Nvidia line. The 1070/1080 are already enough for your needs, so the only benefits you'd see waiting (which, we have no timeframe for... rumors are spring 2018) would be possibly better power efficiency, or maybe the 1160 being capable of handling 1080p/144Hz, and thus you'd save a bit of money buying that card for ~$250 in the spring of 2018 rather than dropping $400-$550 right now... realistically though, I'm guessing you'd need an 1170 anyway come the next line-up, meaning you'd be spending about the same amount regardless.
tl;dr: Check benchmarks, if the 1070 is good for the games you play, get that, but either way, strongly consider spending the extra $50-$100 to get a 1080 for the long-term benefits.