The whole situation is just a mess.
I have been assured on this site that two years ago, people both in Northern Ireland and in the Republic of Ireland expected this to cause major problems, only to be laughed off by Brexiteers. (I didn't give this particular situation not that much attention back then).
Your colleagues can say what they like, but if the UK leaves without a deal, then there will be no "backstop" (the only solution to the problem that is not totally unacceptable to anyone), so there will have to be some kind of border. On the other hand, a border will lead to all kinds of trouble, so we can't have a border. All in all, a total shambles if the UK leaves the EU with no deal.