It might be subject to Disney negotiating new deals with each provider,
I actually don't expect the + to be completely free. Or only on select tiers. The Direct TV agreement last year allowed for the ad versions of Disney+, Hulu, and ESPN+ to be included on select tiers. Guessing it will only be on the tiers that get the RSNs. But they give away ad versions of Disney+ and Hulu all the time because they make more money off the ads than the subscriptions.
This will be in the $100 a month packages and not the cheaper ones.