Exchange delegation federation cert expired.

Hi,

The cert has expired. I looked into it on the web to find out what this cert  is really for and I found, that these functions can only work between the organizations if the cert is valid:

Free / Busy queries
MailTips
Out of office status
Profile pictures

The environment is an Exchange 2013 - O365 hybrid configuration and we  generally don't use these features, but we still need to migrate some of the local mailboxes to O365. 

Do I need to hassle with this cert to migrate mailboxes or I can leave it as it is? Our fnal goal is to shut down exchange 2013 anyway.

Thanks,