Although possible, I wouldn't say the lack of trainers that spot the player instead of having to talk to them to be an indication of the final game in that respect. The only trainers that could be faced in the demo are important ones/rivals, and from what I can remember, those were always event-based, not based on line of sight.
That said, it would be an interesting change if they made all trainer battles happen by talking to them.
That said, it would be an interesting change if they made all trainer battles happen by talking to them.