The shortcut can be changed by modifying the file
FileNameJoin[{$InstallationDirectory, "SystemFiles", "FrontEnd", "TextResources",
Switch[$OperatingSystem, "Windows", "Windows", "MacOSX", "Macintosh", "Unix", "X"], "MenuSetup.tr"}]
Specifically, look for
MenuItem["Inline Free-form Input",
KernelExecute[AlphaIntegration`LinguisticAssistant[InputNotebook[]]],
MenuKey["=", Modifiers->{"Control"}], MenuEvaluator -> "Local"]