I saw similar point systems in Pathfinders implementation of Druids and I didn't care for it. Honestly, how I'd do it is have some subclasses offer unique forms (a swarm form for a spore/vermin Druid), a few niche forms that are accessible by feats, and maybe a few spells that you can cast while wildshaping that will augment your wildshape. But those are all buy-in, keep the core druid more or less as is, just fix some of the numbers.