Assuming your camera, card reader, or other device fully conforms to the SDXC standard, Sandisk has developed a half-terabyte (512GB) memory card. Beyond being gigantic, it can be read at up to 95 MB/s and written at up to 90 MB/s, which should be enough to stream 4K video. Sandisk claims that it is temperature proof, shock proof, water proof, and x-ray proof. It also comes with a lifetime warranty and "RescuePRO Deluxe" recovery software but, honestly, I expect people would just use PhotoRec or something.
It should be noted that the SDXC standard covers memory cards up to 2TB so it will probably not be too long before we see another standard get ratified. What is next? SDUC? SDYC? SDALLTHEC? Blah! This is why IEEE assigns names sequentially.
The SanDisk Extreme PRO UHS-I SDHC/SDXC 512GB memory card should be available now, although I cannot yet find them online, for $799.99 MSRP.