If the Army doesn't pick up the A-10, then the Marines certainly would.
In my opinion, the only way the A-10 goes away is if the Air Force comes up with a direct replacement for the A-10's CAS, and the "Swiss Army Knife" F-35 isn't it.
Never underestimate petty political squabbles between the branches. I could see the Air Force retiring the A-10, not providing a viable replacement, and simultaneously working to prevent other branches from using them.
Those discussions took place during the GWOT when the Marines were still engaged in the Middle East. Now they are pivoting to confront China and expect to fight on islands in the western Pacific Ocean. They have no bases in the area where an A-10 could even use to reach the expected battlefields. Marine Corps leadership has clearly stated that going forward they only want aircraft that can operate from amphibious ships. Most of the airframes are also getting worn out and will be increasingly expensive to maintain; the Marines simply don't have the budget for that.