Unfortunately that’s a feature they’ve been dangling in front of us for a couple years. I think it’s unlikely it will be released before amazon’s extended holiday return period ends.
I believe that with tech products, it’s important to make purchase decisions based on what a product is currently capable of doing. Promises of future add-ons are often delayed or never even released.
In my case, local storage for blink cams would be a bonus, but the primary reason I got one was the totally wirefree design, and overall I’m pretty satisfied with that.