Storage is not 20-30 cents/kWh. Storage alone, provided by Solar City in Hawaii, is 14.5 cents/kWh as of this year [1]. These costs will only continue to decline [2].
The price of natural gas will increase again [3] (and currently, its closer to 7-10 cents/kWh, not 6); when that does, it only makes renewables more competitive. Renewables will never get more expensive than they are today; coal will be gone in the next 3-5 years, and natural gas not far behind.