Like you, I haven't heard anything one way or another, but I'll be mildly surprised if they allow for live streams of the Disney cable channels (e.g. Disney Channel, Disney XD, etc.) inside the Disney+ app. I think the overall content bundle and desired image of Disney+ (always ad free, 4K HDR, major movies, etc.) is more premium than the general perception of their basic cable channels. And they want people to understand that Disney+ is a totally standalone on-demand subscription service (like Netflix). So, from a marketing perspective, I think they would frown on adding in live streams of the linear cable channels with TV provider login credentials. I understand that ESPN+ (which replaced the old ESPN app) does this but I think that's a different situation.
I do wonder, though, if we'll see Disney+ offer next-day (or even same-day) access to new episodes of current-season shows from the Disney basic cable channels, the same way that Hulu does for ABC, Freeform and will start doing this weekend with the new FX series The Weekly. Just how willing are they to cannibalize the basic cable bundle?