Depends what you are preparing for. If you think automation is going to happen but that capitalism will survive, then index funds seems line a good idea. If you think capitalism will be supplanted, it depends on what you think will replace it. If we're looking at a Mad Max style dystopia, then sure, it won't help to have lots of shares. But presumably you'd see signs of that before we get there and be able to start converting your money into harder currency.

If we're looking at a benign-ish revolution with redistribution it won't matter much.

Personally I think the most realistic medium term risk scenario to protect against is that capitalism will hang in there, but that jobs become more scarce. An outright economic collapse or major social upheaval is likely to take more time. If you start seeing job scarcity hitting, then sure, start converting some of those index funds just in case things accelerate in the wrong direction.