Well....If the story writers leave the rest of the story to my imagination, then I would have the story further as follows:
Tappu easily succeeds in her plot of getting Iccha married to Vansh. This whole episode gets hidden from Veer till the last minute. Deeply heartbroken Veer goes half mad and becomes a Drug addict. .....
Tappu will get her share of lesson for not getting what she loved/desired...ofcourse thanking Nani a lot. Iccha will learn that sacrificng always to become a martyr will fetch no good always. Most importantly, Mai will also learn that she should have thought of the consequences of her second son due to her partiality. Vansh who wud be wiser now, will repent for not asking Iccha atleast once what she wanted/loved before acting crazy like a maniac.
If Thakurs get to know all this, then Tappu again earns wholesale hatredness from all and Nani gets thrown out from the house for ruining so many lives.
Moral: Be Good, Do Good....most of all Be Realistic.
I guess, this should be a good way to end the story.
Open to feedback. :)