I was talking about wireless transmission making wires unnecessary, which means we don't need to break the skin. Today's bandwidth isn't good enough, but that in five years might be enough for, I dunno, real-time single-cell recordings or somesuch.
You're still talking about putting done device under the skin. Wires out or no. Pretty much every organ of your body has immune cells that will be on the lookout for a metal / coated coated object. For example, single cell neuronal recordings are done with electrodes that pick up on the induced electrical field of those cells firing. No breaking of cell membranes involved. But they are still notorious for losing signal after a month (in mice) as the glial cells in the brain form a scar around the device.