Bangladesh consigned the Blackcaps to their first Test loss at home in 17 matches, which was also the first time the tourists' won a match in New Zealand.
"With the amount of skills they have and the passion and playing numbers they have over in Bangladesh, there's got to be a time at some stage where they have a line in the sand moment they don't retreat from. I really hope this is it, it's not just a one-off," said McCullum on SEN Test Cricket.
McCullum mentioned how Bangladesh have ignited hopes of being competitive in the past but then failed to live up to the early promise shown. "We've seen a couple of false storms from Bangladesh before, even as recently as their T20 side toweling up Australia in their own conditions, toweling up New Zealand in their own conditions, then showing up to the T20 World Cup and being incredibly disappointing."
What makes McCullum hopeful of the Bay Oval victory to be a turning point for Bangladesh in order to be a consistent side in international cricket? "I think it could be it because I look at their squad and I see it's a young squad and their skill set they possess is capable of being able to travel away from home and glean some success."
"So, I really hope - as tough as it is for a former Kiwi player to look at the result and be okay with it - I look at it and I just think it's got to be good for the global game, and I hope this is that moment for Bangladesh."
Bangladesh are now leading the two-match series 1-0 with the second Test starting from January 9 at the Hagley Oval in Christchurch. The match will also be the last time Ross Taylor will feature in a Test match for the Blackcaps.