isn't kinda obvious Law is now the one designated to the D stuff. His flashback was about the CD v D stuff and his goal is to learn about it.
Yeah but that’s not an interesting or unique thing to do with him.
Finding out what D means has always just been a part of Robin’s dream, well before Law was even thought of. Law’s not getting to Laugh Tale, so he’s not going to accomplish it himself.
Of the D’s, Luffy, Blackbeard and Vivi are more important going into the finale as Imu’s targets and in Luffy and Blackbeard’s case, just in general throughout the series (depending on what happens with Vivi, she may also end up in that bracket to a lessee extent than the other two).
Dragon, you would imagine, will also be more important than Law since he has done nothing so far in the series and that is surely because he‘s being saved until the end.
Plus with Cobra’s last words, Luffy and Vivi (Vivi more so than Luffy, given their respective personalities) are also going to be actively looking to find out what the D is, so Law’s already not very special dream is further reduced.