It's part of the plan to make USAH path a better choice over CHL. Look for USHL to allow expand the allowance for roster spots to more Canadian/Euro players per team. That ups the talent level in USHL and pushes more players to NAHL. So theoretically it shouldn't dilute the talent level if imports increase.
NAHL's biggest competition is with BCHL. More kids, even from New England are going that route. Kids who maybe can make a USHL roster as a 3/4 liner are opting to try BCHL for top 2-line opportunities.