1) Samsung does not need more "space" of its own 64bit chips. They have enough wafer quantity to produce everything they need.
2) You can't take a chip design from Samsung and just start produce them at a GloFo foundry. You need a new tapeout, testwafers, verifying and probably re-spins.
According to Semiaccurate.com Apple already have a foundry/plan. Its behind a paywall, so I dont have any details. Semi are usually correct about foundry rumours.