Good point. She doesn't have a plan which is why Mota Bha keeps telling her what about her when "Krishna and Radha grow up". He said that the first time too when he heard about the deeyarvattu, and Gulaal keeps saying that she has all of them indicating that she will continue to stay with them. She has no plans for herself after marrying Kesar and Talli, she just sees her role as keeping the family intact for the rest of her life and fulfilling Vasant's dreams. It is silly for her to have no plan at all. It just shows how little she values herself and her life.
You are right, it will be awkward if she stays in the same house after Kesar & Talli's marriage (which is only in her mind), she thinks they can continue to live like that with her being a foster mother to Talli along with Sudha and babying Kesar. For someone who has had to bow to customs/society (deeyarvattu), she seems pretty naive.