I actually can see this working better then Paige and JJ ever did. At least JJ and Gabi can not only relate about Paige but can also understand each other on making mistakes in life in which they turned their lives around.
The only obstacle I may see is Jennifer getting in the way of JJ being involved with a young single mother in her eyes pass some judgment. Let alone Gabi did kill Nick, JJ's cousin, so doubt any of the Hortons, except Hope maybe, would be as forthcoming to Gabi especially Julie.
Don't even get me started on Julie and how JJ may have to disown her.