DavidMT, you are assuming that the autonomous ships of the future are going to be just like the ships you are serving on now. They are not.
The people who are planning this are not ignorant of how machinery and equipment on ships function. In fact they actually consult those who are serving on existing ships to hear their grievances and tap into their experiences to ensure that lessons are learnt and solutions found. Once they are ready to send one of their autonomous ship to sea, they would have come up with ways to ensure that it is safe to do so.
If a fuse on a Reefer Container blows there will be a redundant system in place, if that is deemed necessary. Better still, make sure that the refrigeration systems used are 100% reliable. Besides, what do you put in a single container that is worth a million dollar?
To have crew on board to change filters, or plug leaks would defeat the purpose. 100% redundancy is the answer. Expensive to build, but cheap to operate. DP 3 vessel are already required to have 100% redundancy on all essential systems.
Who is going to be in charge has been discussed above, but it is NOT going to be anybody on board the vessel, since there will not be any. Nobody will be chipping rust, or maintaining the OWS, and no lock need to be placed on the O/B valve.
Get used to the thought that this will happen, but probably will not affect the present generation of seafarers too much. A few may move from sea to land to operate ships from the Control Centre, others will do maintenance while ships are in port, then go home.
Yet others will program the vessel computers for the next voyage, plan loading and discharging and ensure stability at all stages of the voyage. Ballast water exchange will not be necessary, as there will be Ballast Treatment Plants on board. (Hopefully USCG will get around to approve some by then)
Don’t fight it, it will happen anyhow. If you want to see the world, fly. It is cheap, fast and easy to get to anywhere.