Well, reddit had chat and we weren't allowed to have it because they decided they didn't want to create an AP for 3rd parties to use.
I wouldn't presume Lemmy will lock features to its own app or site in an effort to monetize them or keep their users in their own apps.
I expect that ljdawson will bring in the features of the Lemmy site over to the app as he sees fit. And that we'll have a pretty complete experience.