I think seeing this primarily as a joint doctrine issue is, frankly, nonsense. It is a failure to use those capabilities you already have, and fixing the technical limitations of your equipment. Look up the report on the Patriot battery which fired on the RAF Tornado.
The one doctrine change which would help? Integrate Army fixed anti-air/anti-missile assets underneath an AWACS/JSTARS or COAC controller. Battalion and brigade level air defenses could remain autonomous - but note that US troops haven't been attacked from the air since Korea.
As for a Space Force? Why? Tell me what effect you hope to create by establishing a separate Space Force. It is better to keep the communications, surveillance and other space assets under actual trigger pullers, who use those technologies specifically for war fighting. Instead you've got a new 'armed' service that has satellites for the sole purpose of simply having something to be responsible for.
At the same time you talk about joint warfare, you're saying we should establish ANOTHER armed service. If anything, we should be talking about integrating the ones we already have.
Correct. US troops have not been attacked by the enemy from the air since Korea.(discounting the Scud attack in Saudi). But we've had some troops attacked from the air by friendly fire.
I still think that Joint Doctrine is key. Army isn't going to put deep battle forces under AF control. AF isn't going to let go of interdiction.
All of the arguments are old. A new order needs to be established.
By establishing a separate Space Force, and moving a lot of intel under it, I propose to establish a one-stop shopping place for all of the Services to get imagery and intel. ATOs or STOs can still be requested by the theater commanders. But the AF doesn't have any business running any platform over 60K ASL. (IMHO)
/john