I think this is partly speculation/wishful thinking in the article. Terry's mentioned before about her perhaps writing for Discworld 'if she wants' before Narrativia was formed. At the con the focus was all on The Watch and her contribution to the writing for that and working with Guy Burt in the driving seat - I think really that's all this is to do with for the time being.
Writing for games/TV/comics/film (remember she's lead writer for the Tomb Raider reboot) is a different discipline to writing books after all. She did say at the con that she had ideas for new characters like a forensics Igorina for The Watch, so that's something new she wants to do and maybe this will have a knock on effect when her Dad leaves it, but she's not actually said anything about taking on the books side of things, so perhaps the article's making assumptions on Terry's blessing being there for her to pick it up 'if she wants' when he's done?
Or maybe it'll be just be her writing Discworld for a continuing visual media franchise which she is after all known for and obviously excels at, leaving the classic novels to stand as a memorial to her father?