If Pacnhali was married only to Arjun, the war would not have happened. In this scenario, Panchali would not have been that relevant anyway, as she is not the empress.
Now would they have invited Arjun for the dice name? Probably not. What do they gain by inviting Arjun for the dice game? He does not have a kingdom to offer. They would have invited only Yudhistir, the emperor, for the dice game.
For whatever reason, If they had invited Arjuna for the dice game, I think he would still have accepted it based on Kshatriya dharma (to the best of my knowledge, a Kshatriya cannot back off from this situation) But he probably would not have staked Panchali. In any case, Panchali just being Arjun's wife is not that interesting for the other side. Even if he had staked Panchali, they do not gain anything by dragging her to the court etc.. The other brothers being free would have started a war, but again complete destruction would not have been possible just by insulting Arjun's wife.
Everything in Mahabharat was destined to happen.
Edited by sanaasr - 11 years ago