Krishnan, are you commenting on my response or the orignal post?
On #1, I think unless one really prefers local execution without having to run a server instance, it's really not necessary. To me, that's a nice to have feature that's more work to implement to embed the server functionality into the local driver to make it easier a bit for users. Because the workaround is simply to use RemoteWebDriver and connect to instance of the server (whether in Grid mode or not). At last check, there weren't local bindings to SafariDriver in all languages, no reason why need local bindings for AutoIt/Sikuli type drivers. I believe even Appium and ios-driver don't provide local bindings.
On #2, that is definitely a requirement. But it's mostly server side functionality. Except for custom commands that deviate from the standard JSONWireProtocol, if you can map AutoIt/Sikuli commands (click, type, find, screenshot, etc.) to the WebDriver equivalent, then you can reuse existing protocol and codebase. One can then choose to modify the shell/skeleton of Selenium Server source code (in Java) or the one for ios-driver or Appium (in node.js or old version in Python) to do what you want. Those source code already contain the wire protocol handling, you just remove out the code where after the command is received and parsed, how it translates to the actual browser command to execute, replace that with what you want to do in AutoIt or Sikuli. Half the work is already done for you using those exsiting servers. Problem is figuring out how that code works by analyzing source code & making the appropriate modifcations. It's probably easier this way than to build your own server from scratch in my point of view (unless one is talented). And from this elaboration, one can guess that you can simply reuse existing WebDriver client bindings for AutoIt/Sikuli without modification. Where you do have to deviate, if you follow the Appium approach, you can keep it simple by using the javascript execution API/command to execute commands/code that doesn't conform the WebDriver API. For Appium, that was to execute mobile specific commands/features, you can do similar with AutoIt/Sikuli.