Li Shenron
Legend
One option would be to do what they did with Turn Undead for the Cleric - make Wildshape a spell that's always available to the druid, but requires the use of a spell slot to cast. You could even have different level versions for more powerful wild shapes.
I am not sure I like it for Turn Undead, but for Wildshape it might work. After all it's not that different from the polymorph spells.
BTW, Animal Friendship was a spell in 3.0, and IMHO it worked even then, although it was very different because since it had a permanent duration then the fact that you needed to prepare it worked mostly for giving the druid a 1-day delay before summoning a new animal companion.