Well, certainly, it's an interesting exercise in "What If...?"
Of course, as stated, it's also a completely pointless one. An official x86 AmigaOS can't exist in the current legal framework. And, if it could, would it really be that much different from AROS?
And, just my 2c worth... With as long as I've been hanging around the Amiga scene, I've still never even been in the same room with an Amiga running OS4.x. In fact, with as many long-time Amiga users and fans as I know, I don't even know anyone within 50-100 miles of me who has seen it either, let alone owns one.
So, that too is a very different dynamic when making a purchasing decision. For Linux or AROS, I can throw a Live CD in my workstation. For Mac OSX, I can go to the local Apple Store or stop over at any one of several people's houses I see every day and play with one. Ditto for any version of Windows, plus there are hundreds of local stores with floor models.
AmigaOS 4.x? Maybe it's the best thing to happen to computing since the keyboard replaced punchcards. I haven't seen it. All I have been able to see are the prices, specs, and a few grainy YouTube videos of it doing nothing particularly exciting. That's all the information I have available.
And it doesn't thrill me. :-( Certainly, anything that could reach out to people better than this would have to be a boost.