You can maintain strong gameshape with 7 players if you learn how to do it right and train gameshape each week. And you will have significantly stronger starters because you have higher salary cap because you have less players.
Having just 7 players is effectively stating to your rivals you have no intention of winning or even competing in the cup.
With salaries dropping and 2 of your 9/10 players potentially being quality 50-70k SF's, there is no reason why you can't build a monster 9-10man roster and compete across all fronts.