I think although this is the more logical route - I don't see it happening without a leap. They don't have the budget to let go of RR mansion as a shoot location IMO. And they'd have to foreclose / auction of RRM to pay the custom duties.
There'd have to be a lot of redressing of RR mansion location to make this work - like they did with the salon episode (lol) - because they'd have to show them in a smaller, more run-down home.
I mean, anything is possible right now but idk. Maybe he puts the house in his sister's name, to protect it from being auctioned, that way his family always has a place to stay, which then paves the way for Sunny to get the house. But idk how that would work with the mental breakdown/instability angle.
The creatives have made Keerti blind in Sunny's love. The only way that illusion is going to break is when Sunny himself breaks the relationship because there is no benefit left for him to stick around her. If Keerti has the house then Sunny will not leave Keerti. Let's see what they show. So looks like Abhishek has died and that is the only way I can see Pallavi leaving RR because Abhishek was like Nikhil to her.