Possible to replace worn out NAND chips in solid state drives?
It would be possible in theory, but in practice it would likely require detailed knowledge of the controller architecture, and possibly some debug tools that only the manufacturer would have.  The reason is not because of a unique ID (most NAND chips will indeed have one, but most controllers won't care), but rather because a "blank" drive will generally not have a blank NAND chip.  Rather, because of the indirection and wear leveling algorithms, the controller needs to read some data from the NAND when it boots up in order to know what's stored where, and if it can't (because the new chip is completely blank) it will generally enter some error state.  Simply copying the data from the old NAND chip will likely also result in an error state, because the indirection table's size will not match the size of the NAND.  You would need to know how to tell the controller to rebuild that indirection table from scratch.  Sometimes manufacturers will provide tools to do this (generally to large datacenter customers, under an NDA), but notebook manufacturers typically will not.