Depending on your definition of drastic changes, the Adventure Force Commandfire which is a hopper-fed dart blaster and the Nerf Chronobarrel chrono/dart counter barrel attachment that are coming out right now. Was the Nemisis already out? Kronos? Adventure force has a Nemisis now and is also selling darts and HIR-clones for almost as little as what you pay online but in Walmart, Jet released the CEDA and finally shipped it; I don't understand the hype because it's basically a lightly modded retaliator or an under performing Caliburn for about the same price as an assembled Caliburn. Worker came up with the Swordfish Stryfoid clone and the Prophecy retaliator clone. Those are the couple big releases that are important.
In homemades land, I made the Mk-13 (and retired it) and the Mk-15 printable stryfoid blaster, Turok released the T19, MHP made a few Katana-mag blasters, katana-mags got knocked off in printed form, FDL became a business and released the FDL3 closed-source but open-sourced the FDL2, Northeast designs released the Chimera (bullpup caliburn), Singapore knocked off the Caliburn with a closed-source blaster with minor changes they're calling the SAB and claim that they made it whole-cloth (and sell it for like triple the cost of a Caliburn!), 498 Nerf made the MBS 2, Gdop made the Spring-thunder shell fed shotgun springer, Tantumbull came out with openflywheels which allow printed flywheels to actually interface and work with regular motors, OOD released his Jupiter HIR sidearm.... There's a few more I'm missing but they're largely plays on the same thread - semi/full auto flywheel or springer that reuses caliburn parts.