If a definitive edition was merely a cost-benefit analysis, would that stay true to Larian's ethos when creating BG3 to begin with? The game is an artistic tour de force - while it may not be perfect, it's success is undeniable to the majority.
By enhancing their current magnum opus, they not only pay homage to their dedicated fan base but also set the stage for unparalleled future successes.
It's not a matter of 'if' there will be a DE. It's the fact that while DE improved DOS 2, it also kind of had to and the end result is still weaker than the rest of the game. A DE on the level of what they did before is likely to smooth out what's already there, not massively change it. Content added in the way of epilogues I could see, content added in the way of Act 2 and 3 living up to the standard Act 1 set, not likely. More banter recorded, main story is probably always going to be a bit of a clusterfuck at the end, etc.
In other words, I think the expectation is for 'good enough' rather than actually 'finishing the game.'
