Micro Segmentation replacing physical firewalls?

Hi guys,

Two of my colleagues went to a conference and were told "micro segregation" is replacing firewalls and hardware firewalls are "outdated" but they do not know the details on it or what it actually is. I find this hard to believe firewalls are being replaced

So what is Micro segregation and how does it replace a firewall? Sorry for being so vague i have tried to google and it is not helping me find any information to ask a better formed question.