Kind of, but probably not what you're looking for.
Your plugin can certainly do a
MyAssetFileModel extends AssetFileModel and (in the scope of your plugin) take advantage of existing
AssetFileModel methods and properties and override them as needed. But that's the catch... it will only be within the executing scope of your plugin.
There's no native way (without hacking core Craft files) to tell Craft "use
MyAssetFileModel wherever you would normally use
However, this is certainly much more doable in the upcoming Craft 3 release since Yii 2 has native support for things like service locators and dependency injection.