Just a little more investment is needed right now, which will gradually grow. Most of the basketball players are too tall to be football players anyway and for NFL you need different physical attributes. The kids with height between 1.70-1.80 or even 1.85, who show talent for football, can continue playing it.
Especially those with Latino origin, or Italian, Balkan, Russian origin etc.
But the popularity must grow somehow so Rossi and Subotic won't play for other NTs.