This one slipped under the radar during E3 week, but IGN have noted that during one of Capcom's livestreams during the event, Monster Hunter: World will be getting a brand new dynamic difficulty system, and it's not just for Iceborne, either.
Previously the game only had two difficulty levels, those being different for singleplayer and multiplayer. It was pretty simplistic, basically doubling the HP of enemies when you were playing with others. This made the difficulty pretty trivial in a party of four, for example.
It had some drawbacks, too. If you were playing with a friend and they dropped out, for example, you were suddenly facing an enemy with twice as much HP as solo players were supposed to handle.
The great thing about the new dynamic system is that it scales back and forth when people join and drop out of the party - and there's a new scaling level of difficulty too where two player hunts are more difficult than single player, but easier than three or four player.
The new system is currently only available on the Iceborne beta on PS4, but it will be coming to all versions and the base game, too, although we're not sure exactly when the update will roll out, although logically you'd expect it to be alongside the Iceborne DLC later this year.