If they can get a good new actress, she can just as easily play Draupadi, and then they can give her a much more major role and return to the Mahabharata story. I don't want them to get a Rukmini who's even worse than Priya. Pradhyumna was very handsome, and Mayavati was the incarnation of Rati devi, so they can't just put any Hidimbaa like actress in her role. So essentially, they'd have to audition for 3 new roles, in addition to Shambara.
Otoh, w/ Mahabharata, they pretty much have everyone, except Draupadi, Karna & Subhadra. So they'll need 2 actresses - one almost a cameo role (Subhadra's) and one major one (Draupadi). I guess it is theoretically possible not to have Karna @ all. But w/o getting Draupadi, they can't get the Pandavas, w/o getting the Pandavas, Krishna will never get to kill Jarasandha & Sishupala.
Hopefully, by the time they finish this Paundrak track, they have found their Draupadi and can restart their Mahabharata track. Another alternative, if they want to bring show Pradhyumna - have Priya do a couple of cameo appearances as Rukmini, and then show Pradhyumna & Mayavati. That could eat up a few weeks. Only thing I'm wondering - will they risk losing some of their Mahabharata actors during such a long interval?