So no, there is no indication of what the specs of Volta gaming cards will be.
Many people had the understanding that Vega would be better than a 1080ti.
I agree with that, but...
...there's no indication that Volta for gaming cards is coming out this year. Not even rumours that it might happen. The rumours are a release early next year. Maybe. With unknown specs at an unknown price. It's reasonable to assume that nVidia will probably bring out a very similar range of models as in the 10x0 series with a more than trivial improvement in each model. They could do that and they know that's a successful approach, so they probably will. But what specs, what prices, what dates? Maybe it'll be 6 months. Or 8 months. Or 10 months. It's not like they're having trouble selling 10x0 cards at relatively high prices and yields must be superb after this much time to refine things. So they don't have an urgent need to hurry. Not unless AMD suddenly find Vega 2 down the back of a sofa and it's much better than Vega or AMD sell Vega cards at £300.
By the time Volta gaming cards are out, the rumour mill/hype train for Navi will be well underway, so maybe wait for Navi. The last shown roadmap put Navi at H1 2018, after all. Maybe not very much after Volta for gaming cards.
Heavily modded FO4 with practically infinite settlement budget...my 7950 is not up to the job. Not by a long chalk. I wasn't in the market for a new card when the 10x0 cards came out and I've been waiting for Vega since I was in the market. Now Vega is out and it's mediocre. Waiting another 6, 8, 10 months to buy at the beginning of the next new cycle while using hardware that's way under par for playing the game I like most in the way I want to play it isn't appealing. I think you're right that close to the beginning of a card cycle is usually the sweet spot for buying, but it's too far away right now for me with my 10-15fps FO4 settlements. I could make much simpler settlements, but I want to play with elaborate settlements. That's the toy I want to play with and that's the toy I'm willing to pay another £350 for. Which sounds nuts to me. I've never paid more than £200 for a graphics card and in the past that was fine (especially if you bought 2nd hand - IIRC this 7950 cost me £100) but today it's not. It took me a while to talk myself into it even though I'm no longer seriously poor. Being careful with money is what stopped me being seriously poor and I take care to keep that habit.