I'll have to work on that. Is there no possibility of a crystal dislocation acting as a "measurement"? It should still be impossible to tell "when" a kaon decays in this case. The universe may only be deterministic with respect to objects that commute with the hamiltonian. (For the whole universe, this would be the Universe Conjugation Operator, the most grandiose term I have seen yet.)
Likewise is there an absolute size of an object that can avoid de-coherence? (Assuming that de-coherence happens.)
The point is, that if you create a wavefunction for everything, then you can't do a measurement, because a measurement is external to the wavefunction.
It should still be impossible to tell "when" a kaon decays in this case.
I would argue that if you knew the exact quantum state of the components of the kaon, you could predict the decay. It appears random simply because of the random phase of the wavefunction of the undecayed particle. (The random phase assumption is of course a can of worms).
Likewise is there an absolute size of an object that can avoid de-coherence?
Decoherence of what with respect to what?.