What China Wants for Christmas

Artist conception of DF-21D attacking a US naval task force

I’m still waiting for someone to explain to me how the U.S. Navy plans to defend itself against a Chinese multi-layer, multi-directional saturation bombardment from anti-ship cruise missiles (ASCM) and new carrier-killer DF-21D anti-ship ballistic missiles (ASBM).
How many RIM-161 Standard Missile 3s (SM-3) would the U.S. Navy carrier task force need to intercept a massive ASBM attack? Do they have enough SM-3s and Phalanx close-in weapon systems for an attack of, let’s say, 20 ASBMs and 20 ASCMs at the same time? How about 30 a piece?
Seems like a high number to use? Well, China is aiming 1,500 short-range ballistic missiles, DF-11/15s, at Taiwan. Why not build 1,500 DF-21Ds? DF-21s are only a slightly upgraded variant of the DF-15.
Let’s not forget China’s Russian-built SS-N-22 Sunburns ASCMs (3M-80MBE) on four Russian-built Sovremenny-class destroyers. China procured 500 of these missiles from Russia. At Mach 3 with a 320 kg warhead they are my personal favorite ASCM since they avoid the typical trajectory of many anti-ship missiles by climbing above the ship before plunging down through the top of the deck. This helps to avoid Phalanx’s attempt to shoot it down.
BTW, guess who else has Russian Sunburns? The answer: Iran.
What would happen if you threw in submarine-launched ASCMs and torpedoes? There are suggestions China is also working on a DF-21D for submarines, based loosely on the JL submarine launched ballistic missiles.
Perhaps the artwork above is silly and far-fetched, but why are the Chinese planning for such a scenario, if so unrealistic?