The Witcher 3 does not have a level cap
The Witcher 3 players can continue buffing Geralt into a superman long after the game has run out of challenges.
The Witcher 3: Wild Hunt offers plenty of opportunities to level up as you explore the main quest and story content, so that completionist players shouldn't have too much trouble hitting level 30 and beyond at the end of their slog.
You don't have to stop there, though - push on to 35. To 40. To 50. To - well, what I'm trying to say is there's no limit here.
"There is no level cap," community lead Marcin Momot confirmed on Twitter.
This means you could, theoretically, earn enough levels to unlock and master every single ability on Geralt's skill tree. But doing so would be tremendously difficult: as soon as you ran out of quests to reward you with decent XP, you'd be reduced to hunting baddies in the wild. Even with XP boost items, it would take a long, long time to grind through all those ability points.
The revelation that there is no level cap has triggered calls for a new game plus mode to be added to the RPG, so players can earn XP more efficiently and face tougher challenges in-line with their increased abilities. There's been no response from CD Projekt RED to this proposal as yet.
Personally, I feel a NG+ mode would be cheating a bit. If you want to play in hard mode, do it with a baby-faced Geralt like the rest of us did. (Very briefly, before giving up and crying.)