I actually hope that Yoda’s force ghost effects are left untouched. Force Ghosts always grow to look more real as the person seeing them gets more powerful in the Force. In ANH, all Luke can interact with is a voice, in ESB, it’s a faint, fleeting vision, and after his Dagobah training, the ghosts become much more solid and able to interact with things, or in Obi-Wan’s case, sit down. So it’s a good progression that in TLJ, the Force Ghosts may as well be living beings, as Luke has only gotten more powerful.