'In what sort of even marginally possible war scenario in the next decade would heavy artillery be either a useful or a decisive factor?'
Perhaps my imagination is too limited, but I can't conceive of such a scenario, and certainly not of one in which the next generation of UAVs and related devices could not achieve the same results, at least as efficiently, and a d*mned sight less expensively.
"I worked as a Systems Engineer on Crusader as my civilian job (I'm part time Guard). Believe me, it deserved to be cancelled on mismanagement and smoke and mirrors alone."
Indirect Fire is, and always has been, the #1 killer on the battlefield--the difference is that the fires are no longer necessarily Field Artillery because of the great expanses of the new battlespace.