I am going to say cause I just remembered. Larian has been pretty consistent in saying they had no plans for DLC or a sequel, rather they are not putting any planning or resources to those right now. Whenever asked the answer is focusing on BG3. Their main focus is BG3, and they are going to focus on the main game before anything else. So ultimately I don't think the possibility of a sequel or DLC is what would limit levels.
If that's the case then it's gonna be a big problem for gamers. No gamer, except for few super tabletop nerds, will sit through a CRPG for hours maybe days without leveling up aka having character progress.
5e has many other ways of progressing, such as equipment. Getting unique magic items gives you progress, and ultimately you get through more encounters in a gaming session than a tabletop session so I reckon leveling will feel quicker as a video game. For example, one of my tabletop groups only just got to level 3 last week, while BG3 you can practically get to 3 before you even get half the companions.
