I'm wondering if somehow Talisa survives this and Mellisandre acquires her to have another "kings" blood.
I don't think so - she's already leaving Westeros and likely headed back to Dragonstone with Gendry.
However - we DO still have the Red Priest Thoros of Myr floating about with the BHw/oB, who may get a similar idea about King's blood after having met with Mellisandre briefly during her visit. We already know they will eventually "run into" Kat at some point and are in the general vicinity of the RW down at the Twins. It wouldn't be as much of a stretch for him to get a hold of Talisa and, ergo, Robb's child.
But now I think we'll REALLY be deviating from the written version way too drastically if that happens.