I think its possible but I also think you will run into problems. Starting with the trackpad, the 2015 board is mean’t to be paired up with a force touch trackpad, which the 2013/2014 don’t have. Then the battery, the 2015 battery is different than the 2013/2014. And the LCD, I read that if a 2015 lcd pairs up with a 2013/2014 board, you will get picture but you won’t be able to control brightness. I expect the problem to be similar vice versa.