As has already been said, there is no way that fixed wing aircraft of any kind can replace the capability of artillery, be it tube or rocket artillery.
In an australian context, a deployed brigade would be lucky to get half a dozen fixed wing CAS missions a day. In a contested air environement, you'd be lucky to get any at all. The missions would have to either be pre-planned against a specific target, which means the aircraft wouldn't be available outside of those times and parameters, or they would be on strip alert, which means they wouldn't be very responsive at all against a target. We can't just have CAS orbiting the whole time, the way the US can.
The beauty of HIMARs, as with any artillery, is that it is responsive in an instant. You've found the enemy gun line? Found the Divisional CP? Found a CSS concentration? Found the FARP? A couple of minutes later, you've got rockets in the air to destroy that target. A formation commander would likely hinge entire parts of his plan around being able to find enemy HVTs/HPTs and destroy them. HIMARs or similar makes this process so much more feasible. It's also one of those weapons that provides the enemy commander with a dilemma, and he would have to expend considerable effort to find and destroy that asset. Even a single battery can have an effect far in excess of its seemingly small size.
The good thing is, this government has proven that if there is a capability out there that we need, they will buy it. I don't think even a billion dollar price tag would lead to sticker shock. I think the biggest issue would simply be manning the system, but I bet the army would convince government they could, then find a way to do it later to avoid missing an opportunity.
In an australian context, a deployed brigade would be lucky to get half a dozen fixed wing CAS missions a day. In a contested air environement, you'd be lucky to get any at all. The missions would have to either be pre-planned against a specific target, which means the aircraft wouldn't be available outside of those times and parameters, or they would be on strip alert, which means they wouldn't be very responsive at all against a target. We can't just have CAS orbiting the whole time, the way the US can.
The beauty of HIMARs, as with any artillery, is that it is responsive in an instant. You've found the enemy gun line? Found the Divisional CP? Found a CSS concentration? Found the FARP? A couple of minutes later, you've got rockets in the air to destroy that target. A formation commander would likely hinge entire parts of his plan around being able to find enemy HVTs/HPTs and destroy them. HIMARs or similar makes this process so much more feasible. It's also one of those weapons that provides the enemy commander with a dilemma, and he would have to expend considerable effort to find and destroy that asset. Even a single battery can have an effect far in excess of its seemingly small size.
The good thing is, this government has proven that if there is a capability out there that we need, they will buy it. I don't think even a billion dollar price tag would lead to sticker shock. I think the biggest issue would simply be manning the system, but I bet the army would convince government they could, then find a way to do it later to avoid missing an opportunity.