while I agree with your sentiment, practicalities mean it wont happen anytime soon.

There is a great company doing river cleanups to prevent the plastic from even reaching the ocean.

https://theoceancleanup.com/rivers/

Their model does rely on a steady "stream" of rubbish coming down the river however I think pragmatically that will happen for many years to come until all people either learn to conserve or to be blunt die.