We've had "truly random" numbers for a long time, starting with those based on radioactive decay.

Current hardware RNGs already take advantage of provably random physical processes. Intel's RDRAND implementation is one good example. Yes, it is probably not a "perfect" source of randomness, though one can always take other sources of entropy and mix further. Doing so will always move the output towards a more random state.

I find it unlikely in the extreme that some future tech will be able to "predict" values from such a random stream (like you could with a PRNG given the seed). In other words, your cyphertext based on a RDRAND+ generated one time pad is safe for eternity, unless the pad is compromised.