I'm really not sure what you are getting at like tenial said. You buy a Vega 56 or upgrade your 5 year old rig with a new CPU/mobo/ram. I would do the later if I was in your position. For the GPU, the performance is equal between the V56 and the 1070ti, the V56 is $50 cheaper, Pascal is last gen tech, there is literally no reason to buy a 1070ti over a V56. V64 is also faster than a 1080 by a bit and can be as fast as a 1080ti in a few games as well as all of the aforementioned. There is no reason to buy a 1080. If you can afford a 1080ti then there is a case for that because it's still the performance king. If you want to stay with Nvidia, but don't have the cash for a 1080ti then it's going to be better overall to wait for Volta consumer cards. I would also advise that if you are looking at a 1080ti. Having a fully supported or at least a supported first card is part of the benefit when you buy into a new architecture from AMD or Nvidia.
It's a bit odd to release it now, but it shows A) how much money Nvidia has to blow and B) Nvidia is driven by epeen. They could have easily spent less money and done an ad buy or review buy to promote their overclocked partner cards against V56. However there is a C) the AIB Vega cards are close to release. Maybe Nvidia isn't late and they released the 1070ti to compete against those.