> The new idea is having 512 bit wide memory instead of PC limitation of 128 bit wide.

It's not really a new idea, just unusual in computers. The custom SOCs that AMD makes for Playstation and Xbox have wide (up to 384-bit) unified memory buses, very similar to what Apple is doing, with the main distinction being Apples use of low-power LPDDR instead of the faster but power hungrier GDDR used in the consoles.