We still need to in someway make all plastic biodegrade in a shorter amount of time when exposed to UV or salt water or else the oceans will continue collect and holding the stuff.
Exactly right, but that's also the challenge in and of itself.
How to make a container biodegradable, but not allow the contents of container to degrade it. Even slow degredation will cause a change in flavor for beverages, etc. (real quality issue) Many bottles are meant for very long shelf lives, so the degredation is a serious problem.
The corn and starch based plastics look very promising. I don't know, but probably the solution to them will be a sprayed in coating that only lets them degrade from the outside, much like a soda can.