It's been reported that Dell's powerful Alienware Area-51m gaming laptops will not be receiving panel upgrades to 240 Hz in 2019. More and more OEMs are turning to this particular refresh rate as a major selling point for updated notebooks, but it seems the Alienware Area-51m will be stuck at a maximum of 144 Hz for the time being.
https://www.notebookcheck.net/240-Hz-screen-for-Alienware-Area-51m-not-coming-until-next-year-but-there-are-plenty-of-other-options.419726.0.html