I think this is called tacit collusion. You see something like this with gasoline pricing - major brands will have "competing" stations across the street from each other, but their prices moves in lock step without a race to the bottom.

Memory vendors have explicitly colluded in the past, but they really didn't need to - they just needed to copy their competitors' posted pricing. Presumably that is what they do now.

If there are high barriers to new competitors entering the market, then the situation is unlikely to change.