If the question is seeking to examine how her attitudes towards coveting the throne for her own child are realistic, I think that the epic shows how the power of maya, or illusion, can be blinding. Kaikeyi is subsumed with jealousy that Kausalya's son, Lord Rama, is being shown favoritism. She fails to understand that her own son is so loyal to Lord Rama that he covets nothing that could possible be seen as an obstacle to Lord Rama. The epic shows that the sober judgment of realism can be dislodged when one is blinded by maya, or clinging to illusion. I think that Bharata's mother's reaction is not realistic, but she is blinded by her own illusion and this compels her to embrace something that is not going to be plausible. Her lack of comprehension of dharma, duty, is what drives a wedge between her Dasaratha and herself as well as her son and herself. It is for this reason that her attitude towards coveting the throne for her son will never work and is not realistic. Yet, in this, the lesson becomes that we will never be able to properly function in the world of what is when our judgment and perception is clouded by maya. This becomes evident when Bharata literally disowns his mother and uses Lord Rama's sandals as the governing authority until his return back to Ayodhya, demonstrating how Kaikeyi's hopes were fundamentally flawed and unrealistic.