Certain industries are completely reliant on plastics such as electrical and electronics and there are no suitable alternatives.
Years ago I worked for a company in Brighton and next door was a recycling plant that separated the copper, steel and plastics used in supply cables so even then they were doing their part.
Where plastic needs to be phased out is fashion and food. These are some of the worst offenders. Cardboard and cellophane (wood derived) are good alternatives for packaging.
I noticed that my Sainsbury's have even eliminated the plastic bar code labels on peppers.
One of the main environmental arguments going on with regards to plastic is the so called invisible plastic, ie fibres that come off clothes when they're washed which then ends up in our seas and rivers.
Some people madly overwash their clothes.