Interesting post, but the Standard is already used on lowly frigates, and can't be used on the only destroyers that don't already carry it, because they don't have the appropriate launchers. In addition, the key to your story is this phrase: "autonomous terminal homing". To be effective against the weapons described in your story (high-speed seaskimming missiles, stealth bombers etc.) you have to be able to engage them at distances greater than those possible with only an IR seeker. Otherwise, you end up with an expensive, and very slow rate of fire CWDS. The IR missiles listed in your story all have relatively short acquistion ranges, and (with the exception of ASRAAM)use vectored thrust to compensate for their small window of opportunity to engage and intercept their targets. By comparison, the Standard is large and clunky. It was designed to hit relatively large contacts at long range. The IR seeker in the Block IIIB Standard was put there to increase its endgame lethality against small targets at long range. Not to provide initial autonomous guidance.