Utter nonsense.You can say that we have already seen it on 1060, yes, but people who buy 1060 and 6400 do not overlap. If you ever bought a 1060, your goal is at least 3050 and 3060. Anyone who buys a 6400 as a gaming solution used to buy GT 620, 730 and similar cards. If there are still such players, they have something to replace, the performance gain will be large.
I bought a 7870 for about £120, and then a 1060 6GB for £200.
I today have a i5-12500 without gpu.
The 620 had 1/16 of the shaders of a 680, and when the 730 came out it wasn't even announced, just dumped on the market
Nobody went out to buy a 730, they went out to buy one of the many affordable cards actually good for gaming. When I bought my 7870 I remember considering the GTX 750 Ti for a long time, but the 7870 was the same price and much better. There were any number of bad cards which you would be stupid to buy for gaming, and then from about £100 you just needed to decide how much GPU you wanted.
I would buy a 6400 today, if it was cheaper. Why not a 6600/3050 ? It costs £300, so no way.
At 40% of the performance of a 6600, give me a 6400 for £120 and I would buy it right now.
The 6400 is absolutely a mainstream product, in that the market now where I am is: 1030 - big price gap - 6400, 1050 ti, 6500 xt, 1650 - big price gap - 3050, 6600
Since the price for a good GPU is much higher now, that means that there is room in the market for more SKUs. Whereas the 730 release was just a plop out and it was irrelevant, the 6400 is priced between 1050 ti and 1060 release prices.
That makes it a gaming product in the same sense of 1050 ti. We can't say 'you bought a 1060, you must buy a 3060', if 3060 now is 2x the price of the 1060 then. I thought the 1060 was too much to spend on a GPU, and I certainly would not have bought a 1070, but it made sense to replace the 7870 as being 2x+ faster, so ok I bought the 1060 6GB for more money than I wanted to spend because it delivered good value, so I stretched my budget. Today I would not pay more for less, pay '70 money for '60 performance, that is crazy to me. I would much rather pay for lower performance, than burn $$$ in an inflated market. At least if you buy a cheap card you can game, and can upgrade later when the market is good. Now to pay $$$ for 2-year-old tech and then in 6 months oops, your 3080 priced like a 1090 is now a 4060? Ugh, no.