It's very likely it's been discontinued. Manufacturers and distributors are hesitant to label blasters as "discontinued". It's almost like a curse. However Target has milked the MK-1.1 for as long as their exclusive contract allowed. Now the supply chain has dried up, and that era is ending.
But no worries, the MK-1.1 was the inspiration for the Nexus Pro. And in many ways the Nexus is better and cheaper and more accessible than the MK-1.1 .
So yes, the king might be dead, But don't shed a tear. The future of your nerf arsenal is entirely safe. Long live the Nexus 👑