Any thoughts as to how much longer a 13" 2015MBP will be supported with updates, and how new an OS it will run ? I'm considering the purchase of a used 2015, with all the available ports also as a consideration. I'm trying to avoid all the keyboard problems with the 16'-19' models. If its days are truly numbered with the move to the M1 chips, maybe an M1 is in my future ? Thanks.