"Without containment measures / lockdown"
But just because government does not impose lockdown does not mean there won't be privately driven containment measures
If people see cases mounting, they will exercise caution willingly
Working from home whenever possible
Maintaining distance from colleagues in office. Using private transport. Using sanitizers every few hours
So the hypothetical that we see of 8 lac cases by 15 April assumes people would continue to behave as they did a month back when the threat was v v minimal in India