I would guess there will still be bus service, just not direct bus service between locations served by the Skyliner. Disney would not add the Skyliner without either being able to reduce busses or increase overall capacity.
When one form of transportation goes down, busses provide ability to reallocate resources to compensate. The busses provide flexibility in the system, not redundancy.
We don't have to guess, we have enough insiders telling us that this is the plan. As @GoofGoof said...
There has been no indication that regular bus service would continue to those parks from those resorts. Any talk of that is just wild speculation or in some cases maybe wishful thinking. What would be the point of adding the gondolas if they didn’t take the place of the buses?
Is the thinking of WDW and its practice regarding the Epcot resorts that have ferry service and MK resorts that have monorail service.
This only becomes a question when someone doubts it and then states their doubt as if it were a fact as if they had inside information.
All insiders are agreed: Pop/AoA/CBR/Riv will not have any sort of regular bus service whether at full schedule or a lighter schedule when the Skyliner is running.