According to Tom’s Hardware, which was mining an earlier Chinatimes article, the technology is only coming to the flagship X670 parts only and not to the mainstream B650 and entry-level A620 chipsets.
For those not in the know, dual-chiplets are a modular way to scale up multi-processing performance that's more efficient than bolting more cores to a monolithic die and AMD has used them for a while now.
However, the AMD LGA1718 AM5 socket will come with DDR5 support only. This means the next-gen AMD platform based around Zen 4 or Ryzen 7000 "Raphael" CPUs could be really expensive as DDR5 memory is still pretty exorbitant compared to the far more abundant DDR4. An earlier report had also suggested a similar thing that AMD could delay the introduction of next-gen RDNA 2 desktop APUs due to the high prices of DDR5 DRAM kits.
DDR 5 is the chocolate teapot of RAM design, being more expensive than DDR4, and for little to no performance gain. It is the first generation of mainstream memory with onboard power management ICs (PMICs) and VRMs which, due to the pandemic, are components which are as rare as truth in a Russian Television report on the Ukraine war.
The pricing puts AMD at a pricing disadvantage over Intel's Raptor Lake, which will continue to serve up affordable DDR4 and expensive DDR5 memory, enabling two pricing tiers for Intel platforms. AMD must be hoping that DDR prices will continue to slide.
It would appear that the X670 and B650 motherboards have no provisions for DDR4, and it isn't yet clear if Ryzen 7000's memory controllers even support DDR4. If they do support DDR4, AMD could have plans for lower-tier A-Series motherboards with DDR4 support.