It's always been said that Destiny 2 will be an entire new game where nothing from game 1 will move on other than your character, however you have to assume that it would make no sense to allow the current abilities to move on as not only will it mean having to keep working with the same broken mechanics, but also limiting their abilities to improve on them more. In fact I don't see any reason to keep any of them since in the end they have no names and no permanent mark on the world so even keeping it is really a waste of time for you, and Destiny 2 wont just keep going from Light level whatever the hell it is by then, I think the only thing you'll keep is the grimoire, everything else will be gone. At least If I decide to return for it I wont mind my starting new, my characters are so far behind right now I don't even care if they move on or not.