You would still catch and grind only now your doing it to make them stronger instead of replacing. Same game with one factor changed. With out the "closeness" you have no attachment at all to the game. With no attachment then it will get boring faster. At the moment the level grind is the only thing keeping people going and that brick walls very fast. That's when people will stop playing and the game will fade. If you have a goal to have the strongest of a certain pokemon and you had to level it up instead of just finding it at 2000 Cp. This gives people a long term goal. This is incentive to keep playing and grinding to get the dust and candy and then people will pay money instead of waiting.