I think it would be a bad idea to develop for the near 10 year old consoles along side the current gen consoles and PC technology but I don't think it should be ruled out. We know that the current gen consoles can handle 64 players on large maps so even if it were on a smaller scale, it would still remain at the standard scale for Battlefield games. That being said, any effort put into last gen versions of the game should be a secondary concern if there is any spare time and resources to work on it.
I don't have either and tbh I'm not in a rush but...
150 million Vs 25 million (?) at release consoles shows what makes financial sense. Battlefield is a popular game but it's not FIFA or CoD. It would be great they went balls out used all the technology to make a fantastic game but even then it will still be selling to the same people.
