Some manufacturers are already looking at alternatives. They showed a system recently where the cans are stuck together using an adhesive similar to those used to attach credit cards to the accompanying letter. That seemed to work but as with all things it will take time to change.
Posts
https://you.38degrees.org.uk/petitions/ditch-plastic-rings-on-beer-and-cider-cans?utm_source=email&utm_medium=blast&utm_campaign=9_10_2018_&bucket=email-blast-9_10_2018_
I didn't think these things still existed, thought cans came in boxes nowadays. Shame that drinks companies are still using them.