I also think it's going to come crashing down, but in a different way. Everybody is way too starry-eyed right now, even Nina. Amanda's advice to Devon about making his rights clear provided a clue where this is headed. Abby can say they're all going to be one big family all she wants, but one day Devon and/or Mariah are going to disagree with some choice Abby makes for the child, and Abby won't want to hear it from them.
I wish Abby and Chance weren't involved in this. This forced sense of urgency with them is mystifying, especially with Chance not around. Maybe if Rey wanted a child but Sharon couldn't carry one because of her age and Mariah agreed to be their surrogate, or if Devon were a donor for Mariah and Tessa, it would be more interesting.
I'm sure Abby's condition with the scarring is a very serious thing in the real world. In Soap World, not so much. Steffi had exactly the same problem on B&B and was told she'd never be able to carry a child. Then she had some cutting-edge procedure or chugged Lourdes water or something, and now she's churning out kids like a Pez dispenser.