In hindsight, I misread you as saying that 128GB of RAM on a “basic GPU” is not technically feasible. My reply was to say it is feasible.
Intel is rumored to have a B770 GPU in development, but it was running late and then was delayed to next year since it had yet to tape out, so they are launching their B580 and B570 graphics cards, which had been ready to go for a while, now. That is why the bus size appears to have dropped across generations. Presumably, if they made a 512-bit bus version, it would be a 9 series card. They certainly left room for it in their lineup, but as far as leaks have been concerned, there is not much hope for one. I do not expect them to use anything other than GDDR7 on their battlemage cards.
As for a high memory ARC card, I am of the opinion that such a product would sell well among the local llama community. There might even be more sales of a high memory ARC card for inference than of the regular ARC cards for gaming given that their discrete graphics sales peaked at 250,000 in Q1 2023 before collapsing, which can be confirmed using the data here:
https://www.tomshardware.com/pc-components/gpus/discrete-gpu...
The market for high memory GPUs is surely bigger than that. That said, Intel is likely pricing their ARC GPUs at a loss after R&D costs are considered. This is likely intended to help them break into a new market, although it has not been going well for them so far. I would guess that they are at least a generation away from profitability.
Intel intends for its Gaudi 3 accelerators to be used for this rather than the ARC line. Those coincidentally have 128GB of RAM, but they use HBM rather than a DDR variant. Qualcomm on the other hand made its own accelerator with 128GB of LPDDR4x RAM:
https://www.qualcomm.com/news/onq/2023/11/introducing-qualco...
If my math is right, Qualcomm went with a 1024-bit memory bus and some incorrect rounding (rounding 137.5 to 138 before multiplying by 4) to reach their stated bandwidth figure. Qualcomm is not selling it through the PC parts supply chain, so I have no clue how much it costs, but I assume that it is expensive. I assume that they used LPDDR4x to be able to build a product since they were too late in securing HBM supply and even if they did, they would not be able to scale production to meet demand growth since Nvidia is buying all of the HBM that it can.