You're on the right track, but haven't taken it to the logical conclusion. The Tendency for the Rate of Profit to Fall happens beause of competition, and the floor is subsistence. The less labor constitutes the overall value of commodities due to automation, the lower the profit. That's where Imperialism comes in, and as the global south also automates, rates of profit crumble. There's no scenario where Capitalism is maintained.

Socialism gets rid of that issue by abolishing competition and the profit motive. Rather than for exchange, goods are produced for use.