Thanks for the primer. I’m not sure that the expansion of spacetime will overcome the strong nuclear force, unless “dark energy” means that expansion will ultimately become exponential at some far-distant point. Perhaps more plausible is the notion that as spacetime expands, the effect of gravity attenuates, thus enabling spacetime to expand faster, and so on. If this notion turns out to be reasonably correct then no atomic decomposition (other than from standard decay) would occur.