The lack of backward compatibility could really impact sales of the new systems a lot more than one might think. This is especially true for sports fans. Because of the way that sports games are aligned with the league calendars, they will release for the current generation of systems long before the expected release of the new Next-Generation consoles; and players of these sports games are not likely to wait for the new console at the end of the year to buy both the console and the sports games.
In addition, since many of these sport gamers are interested in multiplayer and in playing with their friends, it would seem a safe bet that they are going to stick with the console that their friends are playing on if there is no backward compatibility.
While none of the sports gaming publishers have announced if their titles will be available at the same time as the new console launches, we have to think that from a development perspective the effort will have to go into the current consoles as the priority, with the 2015 sports titles being the first major effort for the new consoles.