A more serious response this time.
In my view, the arrow of time would not stop, abruptly or otherwise. Everything other than photons, neutrinos, electrons and positrons would have decayed (we do not presently know enough about dark matter if it exists and supersymmetrical particles — if any — to know whether they are stable). However, positronium atoms would still be around, albeit with a typical size of a parsec or more. Plenty of opportunities for them to interact and form structures. So what if it takes petayears for each interaction?