From their FAQ:

Over time as more browsers implement these emerging standards, the foundation layer will diminish and ultimately disappear.

So more or less, they want it to be gone.

The foundational layer goes away over time. Everyone's app gets better/stronger/fast :) The opinionated sugaring layer on top of Web Components (the Polymer layer) won't go away.

That said, one goal is to have a continuous feedback loop with standards bodies to get things spec'd out if it makes sense to add them to the web platform. Similar to how querySelector landed after jQuery made it "a thing".

I can only hope this to be true. I consider such a statement to be aspirational at best.

Polymer IS a backport of a new web standard, which lets you use it with current browsers.