Capcom has said in a shareholders meeting that people should stop asking for a port of Monster Hunter World as it isn't possible.
Monster Hunter World has been one of the most asked for ports for the Nintendo Switch since it came out. It makes sense too. The portability of the console is huge in the Japanese market and the franchise became one of the region's biggest thanks to its 3DS offerings. It would make sense that there is a hunger for the IP's biggest release ever to come to a portable console.
Thus far, the response from Capcom had always been leaning towards doubtful. Well, now it seems completely ruled out. According to Game Informer, during a shareholders meeting, Capcom said that there wouldn't be a port of Monster Hunter World coming to the Switch. That seems definitive. However, it was said that there are plans already afoot to satisfy that expectant audience. Capcom is actively looking to make Monster Hunter games for the Nintendo Switch, so the series obviously has some kind of future on the platform.
My guess, because there was no reason given, is that the game is just too much for the console. It's an impressive game that struggles to run on more powerful home consoles already so a Nintendo Switch version would be tough. That being said, Capcom did recently port Resident Evil 7 to Nintendo Switch by offering a cloud-based version of the game. That means the processing is mostly done elsewhere and the play is then streamed to the device, so maybe that is something Capcom could do in the future. However, for now, maybe don't get your hopes up.