In terms of leagues, sure. Interms of moving from Dortmund to PSG, still an upwards step is it not. If that was his next step followed by PL or La Liga, he would still have maintained his 'upward trajectory' path, where as going to PSG after one of those two is a step back down.
Not that I really think he would choose to go to PSG at his age, myself. I just dont think they can be ruked out so easily, theybare an attractive place too, they have big wages to offer, chance to play with many talented players including messi, easy league to rack up numbers and records in, almost guaranteed domestic trophies, and a right good crack at the CL. Plus huge exposure.