Il keep my note 3 as mine was bought on march 2014 which I only have for two years. Others bought thiers later. Yes it was released in 2013.
Samsung hasnt mentioned anything. I dont know if it will get update. But no harm in hoping even for 5.1.1. But I wouldnt get rid of my note 3 yet as its still a good phone. No marks on it. Still in good condition. I know it will deff support sd card. Samsung has confirmed that. But dont know about removable battery
Have to wait and see.