SO-DIMM format DDR4 memory modules with a capacity of 32 gigabytes begin to appear on the free market. For example, the German Geizhals.de price aggregator provides links to stores where the Samsung RAM Bar (M471A4G43MB1-CTD) can be purchased at prices ranging from 360 to 440 euros. The nominal frequency of the module is 2666 MHz, the power supply voltage is 1.2 V, the delays are CL19.
Even if you take into account the product's novelty, the amount of 400 euros seems too high. For example, Samsung DIMM DDR4-2666 desktop slats of 32 gigabytes have a price of about € 270. At these prices, compact RAM modules will only be used in a few workstations, where memory capacity is essential for professionals. Meanwhile, players will continue to be happy with smaller modules.
Regarding compatibility, the 32-gigabyte DD-DIMM SO-DIMM has the support of at least modern laptops based on Intel's Coffee Lake processors. One of the users of the NotebookReview site reported the successful update of its creator MSI P65.