Here's a friendly reminder of how big the A-10 Warthog's gun is
Today, we saw for the first time the brand new F-35B/C variant's GAU-22 25 mm gun pod firing, and as impressive as it was, it's not even close to the best gun on the force.
What you're looking at above is the biggest asset for, and the biggest argument against, the A-10 Warthog. You can plainly see how the massive, 4,000 pound (including ammo), almost 20-foot long GAU-8 Avenger dwarfs the classic VW bug next to it. The firepower of that gun has become the stuff of legend over the last decades.
But that's the problem; this picture was taken in the late 1970s. As big and awesome as this gun is, much has changed in aviation, in the battle space, and in the world since it was first fielded. Case in point - you just don't see VW bugs on the road anymore.
So while the A-10 still holds the title of best and biggest gun, the close air support of the future makes different demands on a weapons system. Even though it may still have useful days ahead, the A-10's days at the top are numbered.