I still think, sustained growth is impossible in the long run.

Oh yeah, for sure. All production consumes natural resources at some point in the chain, even services. And natural resources are finite. Even if we recycle everything, we'd still have a finite amount we have to work with beyond which we can't expand. If the driving force behind the production expansion is primarily profit growth, then there's no satisfying that. That's an inherent problem with the capitalist system. If however the driving force is the need for making something that doesn't exist - e.g. more tanks, more wind turbines, more scientific researchers, more musicians, then automation can help a lot. But even for purely profit-driven growth, automation would provide a lot more runway than making people work more hours. I know you're not disagreeing, I'm just saying this for completeness. :D