Data merge is an absolute must for me.
I have been waiting for Affinity Publisher for a while now. I was planning that, once the full version of Affinity Publisher was available, I would bring my Adobe Creative Cloud membership to an end and move over to Affinity products completely. But.........I make great use of data merge in InDesign (even if it doesn't always work very well!!!) and so not having data merge is a bit of a show stopper for me.
Adobe must know that InDesign's data merge is a fragile and I have been asking them for a long, long time to fix the problems they have with it but they turn the Adobe deaf ear in my direction. Adobe seem to have turned their searchlight in the general direction of mobile applications and, to me at least, they seem to be doing much with their desktop offerings (please feel free to correct me if you think I am wrong).
And so, I have very high hopes that Affinity Publisher will be a direct replacement for Adobe InDesign. Please, Affinity, let us have data merge in Affinity Publisher and my cup will surely overflow.