A new mainboard that may need new memory. From another comment in thread:

  I have 64GB of DDR4 in my current laptop, and replacing that with the same amount of LPCAMM2 LPDDR5X is probably more expensive than the rest of the laptop itself.

And another:

  I just had my mainboard die, and I was advised there currently isn't another mainboard in stock that works with my old DDR4 RAM