That would work for a support healing spec. But you can support heal fine as full balance.
If you would go offensive healing, you would burn your mana fast. You don't have access to Intensity. As balance you will have max 2.8k mana.
Moreover you are not only losing dmg (Lunar Guidance and Moonfury), you are also losing 4 % hit and some spell dmg reduction. This means that you will need to switch enchants to hit, lowering your SP even more.
Talents as Nature's Focus are handy against hunters and maybe ret paladins and warriors. However when a melee is on your butt, you will want to either run away from it (low armour) or switch to bear to get off a bash and then root/run. Therefore, you are not getting the full potential out of your talent.
In a team heavy on priests and shamans, that spec might be an option though. It would fit a "tab-dot and meanwhile hot up your party" style of play. Again your mana would be an issue.
Edit: For arena, that spec might be quite interesting against priests. IS costs less base mana than dispell. Imagine a priest burning his mana by trying to dispell your IS ^^. Your spec reminds me a bit of the typical 80 resto spec. Only difference is that you don't have all the healing goodies.
I haven't played that spec before (hell haven't even played druid 39 post 3.2 ><). I hope my comments gave you some extra insight
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