Does this new addition point to any other changes on the horizon?
When Steve Jobs announced the original iPad a little over 11 years ago, the experience was designed around use in portrait mode, much like the iPhone that preceded it. While the device could be rotated, many of those early demos focused on using the tablet much like a large notepad. Even the original Apple Keyboard Dock held the iPad in portrait mode, rather than the more natural landscape.
Those origins still inform the iPad and iPadOS, but things are definitely changing. This new Apple logo boot screen is just more evidence of that evolution.