Actually DD's memory loss (if partial) can be used as an effective tool.
It can bring back the golden days of JR (the charm of the initial episodes). I know that DD forgetting all of Sid's sacrifices and blaming him without reason can be tad boring and repetitive as she does that in almost all tracks (with or without actual memory loss).
But if executed properly, they can show the playful yet caring Sid. When JR started the caring nature of his personality was reserved mostly for Roshni; this time it can be for his beloved 'sasumom'. He can also irritate his 'sasumom' (again, I know he does not really need DD to lose her memory in order to irritate her).
I guess the CVs can go a step further and make DD behave like a child. There were discussions/predictions in this forum about either Sid or Roshni losing his/her mental capabilities, then why not DD?
Anchit ji is a powerhouse of performance. I know she would be able to emote those scenes brilliantly. But, the best part about it for me would be Sid in his full-on protective mood. Sid absorbing everyone's pain inside himself, putting up a brave face for Roshni and DD's well-being (even nanima's, if the CVs use her character correctly), would be in tune with Sid's personality.
I would also like to see Sid handling DD's business single-handedly and with unparalleled dedication, taking it to new heights.