I still have my mickey bar bet that there will be no change in the frequency and numbers of buses they have now...on a normal day. Yes mid day has fewer buses, but the rest should stay as is.
So far there has been nothing but rumors and speculation about reducing buses ..nothing official from WDW except adding the Skyliner to the modes of transportation on MDE along with the buses.
When the Skyliner starts running it will take a lot of the load demand off the buses. They will load and unload a lot quicker and not be packed in like they do which takes extra time as they wait for more people to walk up, so they leave quicker and the time for the route will be a lot quicker.
At peak times they normally call extra buses from wherever to get the crowds to or from the parks/resorts. The Skyliner will reduce the passengers for the buses and make them way more efficient where they won't need more buses "at peak times" ....except during the storms.
It just doesn't make business sense to be to not cut back on buses in some way when the Skyliner is carrying even 50% of the people who were riding the bus routes. Maybe they will end up combining some of the routes.