Nvidia hasn't had a calendar year without a GeForce flagship before (although 2011's was simply the dual GPU GTX 590). Since we don't get new architectures every year, they have delayed the big chip until the off year. But with the TU102 coming this year, what's in store for next year? I guess it could be a Titan RTX but there's not too many enthusiasts who went Titan Xp (launched after 1080 Ti), so not too many would pay huge sums again for just a fully enabled TU102.
Something is coming next year. We just had enthusiasts throw down ~$1300 for unknown performance GTX 2080 Ti's, simply because it's obvious they are a tier faster than the 1080 Ti and people want more performance. If Nvidia can get a decently faster 7nm card out in 2019 then they will and they will again charge a fortune for it.
People like to have patterns, so they look at the past trying to find patterns, and when they see one, they think it is some kind of rule that can't be violated. But it isn't. In reality companies just do what makes the most sense to them at the time, and people are establishing patterns in retrospect. So no pattern is set in stone, and they get broken all the time.
Like the "new flagship" every year. What was 2017's "new flaghip"? 1018Ti? That really wasn't new. It was just rebranded Titan X at a lower price. If that's the pattern, it's already broken(because there is no Titan). So really there was no real new flagship HW in 2017. It was just a marketing update. I suppose they could fully enable TU102, and call it 2085Ti as Titan seems dead now for gaming cards. But of course a broken pattern on Gaming Titans could be reestablished. Because these are just marketing game and can change at a whim.
As for real new HW products, I feel fairly certain we will see a 7nm GPU from NVidia in 2019. Targets might be a lower end pipe cleaner GTX 2060. Will be a tiny, not RTX product great perf/watt, and perf/$ and great for laptops. Or they might really want to die shrink TU102 ASAP.
2019 should be a VERY interesting GPU year. With new unknown, unnamed, 7nm gaming GPU HW likely from both AMD and NVidia.
It will also be interesting to see how AMD handles Raytracing, since they might not have specific RT HW in their 2019 cards. Do they do some kind of driver that offers 2nd class RT capability, or do they play it down and concentrate on giving better Raster perf/$?
To tie back to the original topic. RT will soon be table stakes. AMD realizes and are no doubt working on their own RT HW solutions. But given lead times, it will probably be 2020 before they have something competitive.
RT is here to stay and soon everyone will have it on upper end cards.