So far, what I'm seeing is that the 2080 Ti is and will continue to be an improvement while people still make a value argument regarding what is better: Pay less for 10-series or pay 2x as much for 20-series.
The problem with that logic flow is that it makes valuation fallacies. Ultimately, people should pay what they can afford but just because something costs 2x more doesn't mean that GPU farms won't acquire 20-series for the meager percentage gains because the gains can and most likely will outpace upfront costs in the long run as well as preventing losses when new opportunities present themselves.
So if I were to replace a $500 1080Ti with a $1K 20-Series card. I paid $500 more at one time on one day. From here on out, I gain some arbitrary percentage more in performance as well as power efficiency which matters more or less to different people paying different amounts for energy. Unless you are on some sort of deadline, it doesn't matter if the 10-series or 20-series ROIs first. Once they ROI, the 20-series will forever hold the profitability high-ground. On top of all that, it is just as likely that there could be some unique development that only the 20-series could benefit from. Some RT specific algo perhaps.
Now, I'm not going to run out and instantly replace 10-series rigs. However, I am watching the 20-series market closely as I expect any rational person would.
You forgot to say *IF* the 20-series ROIs, then it will hold the high ground. Today the yields are pretty terrible, but there are other innovations round the corner that could make GPUs obsolete; the acorns from squirrel labs; the FPGAs quietly being bulk produced and preorders placed in the background; the fact that POW has a questionable future e.g. Ethereum. These are all imminent dangers affecting profitability within the next 12 months, Acorns are meant to be shipping <1 month.
So I think arguing that paying 100% more for a 10% increase on a card that *might* do ROI in 10 years is a valuation fallacy. But anyway, if you have a fully operational set of rigs I could understand purchasing some additional 2080TIs and expanding that operation, but I can't understand your logic for selling all your existing 1080 TI and replacing with 2080 TI. Maybe you entered the game at the right time and those 1080TI have already paid themselves off so the loss wouldn't be "as bad", but I still think it's pretty nonsensical to be buying hardware that you know has a bad cost:hash ratio- a GPU is never as profitable as the first day you turn it on, so economically speaking in a best case scenario, this time next year your 1080TI and 2080TI will have the same profitability as today.
Just my 2 cents as I have often seen in crypto land that when someone makes a bad investment, they often try to get others to share in that.