I would be worried about it. What will happen is that the lose wrist pin will eventually fracture the piston sending pieces of the piston into the pan. You will then have a piston wrist pin attached to a rod being flung around in the cylinder. That will score the cylinder and/or just crack through the cylinder into the water jacket. That is a worse case scenario though and when the time comes it may just crack a piston just enough to allow noticeable blow by before it disintegrates.
If that happens, then it happens. I'd say 236k miles was a good run. I'll just put another one in it when this one goes.