Currently there is an opportunity for an industrious plastic-eating microbe to hitch a ride in every gut on the planet, deciding the winners and losers of the plastiferous period. All that means, though, is that there's a chance such a creature could appear and take advantage, not that it will happen. (Yes I know plastic-eaters have been discovered, but I'm not aware of any having an effect on the fitness of other creatures.)
It overlaps a whole lot with the concept of a dyson trees, but the core problem is that it needs to be able to use the metal in the first place - earth is a metal planet, in the sense that ~10% of the planet is iron, and yet our trees are not steel.
I also can't help but wonder, could trees even use iron if it was plentiful in the upper crust? You need a lot of energy to separate iron oxide into elemental iron. Betting against what evolution can make is usually a bad idea, but that would be a neat trick.
