I know there's more history to webkit, but that didn't really seem relevant to the rise and decline of IE... I glossed over it for the sake of brevity. (And yes I know, I still failed to keep it brief, despite that).
As for the decision to do a rewrite - sure Microsoft put pressure on Netscape, and that did influence their decision, and sure Microsoft might have killed off Netscape anyway - but the rewrite still was Netscape's own decision, and it was also Netscape who failed to pull it off successfully.