and they can’t just exchange or give their microchip to some one else or rip it out some how?
Yes, I guess they could remove a chip depending on the location of implantation, but . . . A good surgeon just might be able to recover the rice-grain size older microchip, a more than exceptional surgeon might be able to locate and remove the really small ones out now, but it is incredibly hard to locate the chip at postmortem when you are not concerned with tissue damage.