I'll agree on the integration part, but mostly for fixed and rotary wing aviation. I still think the Army's direct and general artillery support is more advanced. A lot of people want the Army to own the Air Force's A-10s, but that would be a mistake. Having to rely on prepared airfields would be a step in the opposite direction. If the F-35 VSTOL doesn't make the cut, that will become awfully apparent.
As a former cannon-cocker myself, I attended the same artillery schools as did army arty officers. Our doctrine is almost identical. Other than the army bought into "big sky, little bullet", and we didn't. Which our pilots liked.
But the Army does have more arty, and more varied assets. So it certainly is possible for the army to put together a more flexible package of arty support for a given operation if it has the time and assets in theater to do so. We just don't have the equivalent of Corps-level artillery. Although that can be task-organized to some extent by adding more arty units to a particular MAGTF package.
The way I've always looked at it, both the Army and the Marines have a particular value that could not be fully replaced by the other. If the Marine Corps tried to get as large as the Army, it wouldn't be the Marines anymore. And if the Army tried to recreate what the Marines have (and they've looked at it one some levels) they couldn't do that either.
We're all on the same side, and in the same boat.