I'd say there's a good chance of them implementing addiction as they had it in New Vegas and it was mentioned throughout in Oblivion.
It's going to be awesome if they do
Especially if they introduce interactivity with NPC's. ie. You can give an NPC some skooma a couple of times and before long they're begging for it... Followed by your extorting them of course 
It's going to be awesome if they do


My characters would do this to anyone who would try the drug.