Compared to the chemical industry, the polymer industrial is pretty undiversified. Just 6 polymers, high density polyethylene (HDPE), low density polyethylene (LDPE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC) and polyethylene terephthalate (PET) dominate the industry. Those six polymers combined make up 76% of all polymers produced. 76%! While the exact number of commercial polymers isn't real well established (the number 60,000 seems to keep popping up), the industry is as clear violation of Pareto's 80/20 rule rule as there ever was.
That dominance really boggles the mind. Imagine if chemistry were dominated that much by just 6 chemicals. That might be a good description of what the chemical industry was like 150 or 200 years ago. And yet that dominance has never directly affected me. I've never worked in the production of any of those 6, (and I've only met one person in my 25-year career who did) which means that I'm a 24%-er who's worked with the other 59,994 polymer chemistries (or at least a fraction of them). And that is more than enough of a playground to keep me going for another 2500 years.
But that other 24% is also where it is easiest to create new polymers of commercial value. Think you can devise a new polymer (especially a "green" biobased polymer) to displace anyone of the big 6? Think again. Those polymers are a permanent part of the landscape. It is a certainty that in the future the monomers will become biobased and fed into the same reactors rather than a novel polymer displacing any one of them. For instance, ethylene can already be made from by removing water from biobased ethanol and there is strong research into creation of biobased PET and PP monomers. No, the Big 6 Plastics are not going away anytime so.