Everybody seems to forget that BG1 only had Level 8-10 depending on class for that story and then Bioware got to build on that to get the rest of the levels for bg2. Oh well...
BG2 DLC TOB reached level 31-40.
NWN1 with DLC HOTU permitted epic level until 40.
NWN2 with DLC MOTB had got also EPIC LEVEL until 30.
So where's the problem for an expansion until level 20th for BG3?