The member schools have the right to alter the format. For instance, 4a west chose a different playoff format last year. They could change again this year if the majority voted for another change.
So the answer is, probably no changes in 5a, but still a possibility.
As far as dates, the VHSL has a master calendar that all schools, districts, conferences, and regions must adhere to. So, the dates will be either the same as last year, or one day different. I haven't looked, and I don't know how this year being leap year affected the dates. But, any change is minimal.
The change back to regions, and the dissolving of conferences, takes place for the 2017-2018 school year. And the regions may very well decide on different playoff formats. I have been told, that the VHSL simply tells the member schools to send us four teams per division, (groups), for the semi-state championship games. And how you get down to them is up to you.