No, Game Freak was smart this time and managed to change the literal linearity of the map without removing the one-city-at-a-time scheme they'd set up for BW. You still need to beat Drayden to get to the Marine Tube and thus, arrive at Seigaiha.
BTW, now I'm at lv51-53 at Victory Road (Galvantula/Volcarona/Starmie/Virizion/Mienshao/Metagross) and I'm feeling something's... weird. My Gross has Hammer Arm/Meteor Mash/Rock Slide/Agility and he can't kill anything. It has a neutral nature and ~144 Atk at lv51 which I think is *acceptable*. Shouldn't it be, like, killing shit instead of just taking hits (it's pretty good at that, I have to admit)?