They could name the new browser something other than IE, and make sure the code testing for older IEs sees it as just another hopefully standards-compliant brow

They could name the new browser something other than IE, and make sure the code testing for older IEs sees it as just another hopefully standards-compliant browser. Then the "if IE" code wouldn't trigger because the browser is Microsoft(r) MetalDog Home Premium, or whatever. Of course they probably wouldn't want to lose the brand recognition of IE.