Possibly, but it's not as abrupt and obvious as with JetBlue/Spirit, who both compete in the exact same market in modestly different ways. Alaska and Hawaiian have limited regional overlap with flights from certain west coast cities to certain islands, but beyond that, Alaska would be getting Hawaii's entire international route network and tying it in with their entire CONUS domestic route network.
The more interesting transaction that arguably should've been stopped was Alaska purchasing Virgin America as they were both largely west coast airlines. But amazingly enough (as someone who held status on VA and later Alaska), my flights actually got cheaper after that merger, and I was consistently upgraded too. So if that merger hadn't happened, my experience would've been worse.
