The very concept of ownership is a social artifact, and as such, is not immutable. What does it mean for the 0.1% to own all the means of production? They can't physically possess them all. So what it means in practice is that our society recognizes the abstract notion of property ownership, distinct from physical possession or use - basically, the right to deny other people the use of that property, or allow it conditionally. This recognition is what reifies it - registries to keep track of owners, police and courts to enforce the right to exclude.
But, again, this is a construct. The only reason why it holds up is because most people support it. I very much doubt that's going to remain the case for long if we end up in a situation where the elites own all the (now automated) capital and don't need the workers to extract wealth from it anymore. The government doesn't even need to expropriate anything - just refuse to recognize such property rights, and withdraw its protection.
I hope that there are sufficiently many capitalists who are smart enough to understand this, and to manage a smooth transition. Because if they won't, it'll get to torches and pitchforks eventually, and there's always a lot of collateral damage from that. But, one way or another, things will change. You can't just tell several billion people that they're not needed anymore, and that they're welcome to starve to death.