I don't think people quite understand what Pan India star is.
Pan India star can be called as someone who has popularity throughout the country, he need not to be biggest in his own industry.
For example whoever is biggest Telugu start currently, has no popularity in Northern & Central markets, Prabhas is popular in north & Central regions though. Similarly biggest stars of Bollywood don't get much collections for their movies in South markets.
Prabhas can be both, a Pan India star despite not being the biggest in any industry. Simple equation.
For example Salman gets 10 crs collection for his movie in Bollywood markets and 2 in South with total = 12
Some South star gets 12 in South and 1 in North, total = 13
Prabhas can get 8 in south, 6 in north, total = 14
Coming to your question, he can be but he'll need to repay this great consistently, he'll need to make his image more than Baahubali wala star and be Prabhas in core hindi regions too, only then you can call him Pan India star, so he's a long way but only he can do that currently, he's got a golden opportunity, let's see what he does with it.