Yeah I could see this tbh...I very much doubt we will see brand new architecture
Depends what you mean by new architecture. Volta (as I strongly suspect the 11-series will be based off) isn't 'new'... it's been around quite a while now in the pro cards, so for Nvidia to repurpose it for the 11-series isn't actually that big a deal for them. Anyone expecting 1180 to be anything more than this is dreaming though. It certainly won't be Turing. On the other hand, I don't see it being a Pascal refresh either... that just makes no sense to me and would be a counterproductive move given the backlash they'd receive.
I see the argument that Nvidia don't NEED to release a new card with the 10-series still selling strong and no competition, but sales have tapered off and there is MASSIVE interest in what they have coming next. Let's also not forget that the gap between GPU releases here is rather unprecedented for them, so a lot of people are chomping at the bit to get something new. Nvidia will be well aware of this, so they don't need to worry about new cards flying off the shelves... which they absolutely will!
If these cards are Volta based, I would predict the 1180 could offer 40% and perhaps even up to 50% improvement over the 1080 in certain DX12 & Vulkan titles (less in anything else), and 10-20% over the 1080Ti... with less power draw. The only question is what they will price it at... but we all know (and so do Nvidia) that people will pay regardless!