>>>>Warheads on the DF-21/26 aren't the same size as the missile diameter

For some reason finding physical radar dimensions is not easy. Even if the warhead is ~1m to the DF-21/26's 1.4m, that's still enough to stuff in one of these: [1] one of the most powerful A2A radars ever. [2]&[3] are <60cm diameter. [3] is known Chinese tech, and is therefore most within the realm of feasibility for employment.

>>>And the missiles won't have that much maneuverability

They shouldn't need much, just enough to turn a near-miss into a full miss (assuming a frag detonation and not a more difficult kinetic kill anyway). Topol-Ms are rumored to have evasive maneuver capabilities, to establish precedent.

>>>>Plus you're forgetting about SM6. This will eat these for breakfast, lunch, and dinner.

Nah I just lumped them in with the SM2/3. Regardless of the actual SAM used you're going to shoot 2 of them per incoming contact. The SM6 tests listed on the Wiki all used 2 missiles per MRBM target.[6]

>>>Assuming that the DF21 can even burn through the ECM that will be blasting it.

Ummmmm, pointing insanely powerful radio emissions into the upper atmosphere in an attempt to blind a ballistic missile is a great way to broadcast your position. If anything, might be a good idea to configure several DF-21s for passive direction finding. Not sure if the DF-21s have any kind of datalink, the speeds and atmospheric conditions will make that difficult, but P-700 Granit missiles have a networked cooperative capability and those things are decades old.

>>>>An 1100lb warhead will be similar in effect to a Harpoon.

A Harpoon has a <500lb warhead [4]. 1100lbs is closer to a Tomahawk. For reference, the P-700's warhead (and it's definitely considered "carrier killer" ordnance) is ~1600lbs.

>>>You might get lucky and have a mission kill

A 500kg warhead with a vertical attack profile, if it hits, is practically a guaranteed mission kill. The CVN will lose catapults or an elevator at the least, and suffer a gigantic detonation inside its hangar at worst. Either way it's a PR victory and its entire air wing is no longer contributing to the fight.

>>>>>And if we go to war with the PRC, we won't be using one CVN. We'll be surging 2-3 CVBGs, and they'll run out of missiles.

If they run out of anti-carrier ballistic missiles they'll send drone-converted 3rd-generation aircraft, which is a great way to burn up our anti-air ordnance.[5] If anything they'll use those FIRST to exhaust our defenses, then fire the DF-21/26s, then follow up with a land-based strike package to finish the task force off. China's land-based strike aircraft all outrange the combat radius of carrier aircraft + ordnance by a significant margin. We'll run out of ordnance within the Nine Dash Line / First Island Chain before China does.

Oh, not that I ever expect a 100-missile DF-21 salvo anyway. I don't think they have anywhere near that many launchers, and our best bet would be Tomahawk strikes from submarines against the launchers early in the war.

FYI: I've spent ~5 years in the west Pacific Theater, 3 of those at a Corps-level combined arms headquarters that regularly wargames ahem a "peer fight" against a fictional country with a ballooning blue water navy and an authoritarian government, if you catch my meaning. I've spent a LOT of time reading exercise AARs, intel updates, and threat briefs from the past ten years on this problem set, courtesy of the ///SECRET Intelink portal. But I'm arguing entirely from open-source info here.

Oh, and check out RAND's site here:[7] It's 2 years out of date but if anything the US's relative situation has deteriorated. But it's a good quick summary of the balance of power.
[1]https://4.bp.blogspot.com/_44d3OT-xI3U/SOke7iN2vaI/AAAAAAAAA...
[2]https://2.bp.blogspot.com/_44d3OT-xI3U/SOkeIyMnjDI/AAAAAAAAA...
[3]https://defence.pk/pdf/threads/jf-17-block-iiis-proposed-aes...
[4]https://en.wikipedia.org/wiki/Harpoon_(missile)
[5]http://aviationintel.com/as-highlighted-on-this-site-as-a-th...
[6]https://en.wikipedia.org/wiki/RIM-174_Standard_ERAM
[7]https://www.rand.org/paf/projects/us-china-scorecard.html