Causal patch complementarity is the conjecture that in de Sitter space with a positive cosmological constant, the states within the causal patch are sufficient to fully describe the universe with the rest of the universe outside encoded within the stretched horizon a Planck length thickness on the inside of the cosmological horizon.
However, it is not at all clear if it applies to metastable phases. In the inflationary slow roll phase, for example, our universe passed through at least 60 e-foldings in a de Sitter phase with a tiny cosmological horizon before rolling into our phase and expanding into the universe we see today. The catch is once inflation ended, observers will be able to simultaneously observe information streaming in from many many causal patches (during the inflationary phase) in all directions. How can this be compatible with causal patch complimentarity? Are all these information not independent of each other in principle? Maybe because for the Bunch-Davies state, most of the apparent entropy between causal patches are really entanglement entropy?
In string theory, all phases with positive cosmological constant have to be metastable at best because the only truly stable phases have to be supersymmetric and supersymmetry is incompatible with a positive cosmological constant. This includes our current phase. Let's assume for the sake of argument our observable universe eventually decays into a thermal equilibrium at the de Sitter temperature and remains that way for an exponentially long time before a quantum fluctuation leads to a tunneling into a new stable supersymmetric phase with a zero cosmological constant. Exponentially many e-foldings would have happened in our phase before that fateful tunneling. In a Penrose diagram, the "hat" describing the new phase will be exponentially smaller in size compared to our de Sitter phase in the Penrose diagram coordinates. So, an observer in the "hat" will be able to observe exponentially many causal patches simultaneously.