If you are going to the extent of having a new 4k Fire Stick and want to be cable free, this is the answer you are looking for and is worth the asking price. The photographs illustrate the size difference between this product for the Fire TV 3 & 4K Fire Stick and the much smaller prior model for the Fire Stick 2.
https://www.amazon.com/Amazon-Mission-Power-Eliminates-Adapter/dp/B078KSHVCS

