I have intentionally run out of licenses in Co-Term for verification purposes.
My environment at the time was Meraki MX, MS, MR.
In that case, splash page was displayed when accessing the Internet.
Presumably, this is a mitigation measure to allow Meraki to renew its license.
It is not explicitly stated, so I don't think it is a guaranteed behavior.
Also, as expected, the file server in the LAN is no longer accessible.
One thing I can say for sure is that the service impact is certain to occur after the grace period.