I am not sure that Mrs Gandhi would have won in 1984. Judging by Assembly election results, the Congress was on a downward spiral.
The mood post Bluestar was nauseating and disgusting. All parties hailed the operation as a major military triumph even though, in military terms, it was a debacle. Only Chandra Shekhar spoke out against it and was shunned by his colleagues.
Doordarshan featured people like General Brar night after night and portrayed him as the conqueror of the Golden Temple. (Read Mark Telly's Amritsar for a detailed account.)
Nobody showed any sensitivity to Sikh sentiments. Most moderate Sikhs were horrified by Bhindranwale. But the government response in the post Bluestar phase upset even the moderates.
Most people date the beginning of Hindu politics to the Bahri Masjid. I date it to the Punjab conflict.