It's plastic, so you don't have to worry about it rusting. It may start to flake off at some point depending on what is holding it together still, so if you can live with the slight defect, no worries.
When it starts to flake off, and it will, then you can decide whether or not to have it painted. You can always try to source a used bumper from somebody, but I doubt that'll be easy to do. It is new enough you can probably just buy a new painted unit from Subaru, if you're worried about paint matching.