We're almost 30 chapters from the end but I kind of bet this doesn't get better. Or if it does it doesn't stay that way. It feels like the ending they'd work towards is Takae getting to say goodbye to her family, pushing her husband to move on, and then fading away so Marika can have a proper childhood life and a repaired relationship with her mom. The husband can maybe give a second thought to finding someone else and try again with the cute co-worker girl, and Mai gets to progress in her relationship too.
Because as sad as it is that Takae goes away, she's kind of holding everyone hostage by being present. The original Marika who didn't know anything of being Takae has been dormant for over a year, her husband is clinging to the idea that if he waits like 8-10 years he can marry a young girl who then has to watch him die while she's still in her 50s/60s, and she really can't have a full relationship with either her current mom (Because she's not a kid and remembers being a mom herself) or her former family (Because Mai can't introduce the little girl she hangs around with all the time as her mother). Marika's mom also has picked herself up and gotten her life together but her "reward" is that she's basically lost the daughter she knew while Marika's personality is subsumed by Takae.
It's bittersweet but it's exactly the kind of bittersweet ending that stories like this love because it gives Takae's return to existence meaning before leaving things better than she found them.