There is a chance we won't get definitive edition. Act 3 barely works on PC, so in few days we'll see how poorly it looks on Macs. How do you expect more things to be added? Now add the new voicelines for Karlach from patch 2 and you see that it's very not likely
To be fair, DOS2 was actually unplayable in the last act. As in a lot of people couldn't even complete the game because of the bugs. I don't think it's safe to speculate there won't be a DE.
