Since the worlds level up as you do (FINALLY!!!!!!) I assume you get more EXP when you defeat each enemy as the world's level rises, so it does become easier to level up compared to past games BUT it does get a bit slower, I completed all the special portals and got all the chests for each world before I moved on to the next so I'm not sure if you'll get that high without some grinding, but who knows. Regardless, I found that when I was close to 50 I was well above the level the final world was, even when it increased to try and reach my level (key word is "try" lol xP)