The mining cards that Nvidia will be realsing will be based on the 1060 from what I have read. Mainly just without a video output. I think performance will be similar, maybe ~10% - 20% better and probably cheaper since they only have a 3 month warranty. The Dag is the dataset needed to be stored in memory for the POW mining algorithm used by Ethereum. It grows in size by roughly 0.73x per year. Current size is ~2.1GB and once it exceeds the VRAM on the card, it can no longer proceses the transactions required for mining. Dual mining is a feature where you can mine two diffrent POW algorithms at the same time, therefore incressing the efficiency of mining.

Nvidia GTX 1060 3GB or 6GB are about your best option out of what is more readily available to put together a rig ASAP with all the same cards, at a resonable cost. BBT posted a video of the 6 card rig he built with the PNY GeForce GTX 1060 3GB XLR8 OC Edition

165+ GPU
1000+ MEM
~23.5mh ETH and ~268 SOL/s ZEC each @ ~60W per card.

https://www.youtube.com/watch?v=1uhSfOpvHks&feature=youtu.be&t=7295

Dag won't reach 3GB until early next year, so you should be good until then. The only problem with the 3GB cards you won't be able to dual mine effectivly.

Precise roadmap - centralization, anyway, I do think that ETH with its huge supply and another supply through its coming PoS will definitely surpass bitcoin in terms of Marketcap, which can give an illusion that ETH is more valuable and being number 1 to a new person in cryptocurrency which in fact we all agree that this coinmarket cap offers nothing other than estimated price of total coins.

It seems to be a very difficult question, because I still could not understand What is the value of the crypto currency. If you take for example the dollar, then every dollar has its share of gold in the state's Gold Reserve. But Bitcoin, it's practically air, which costs fabulous money.