In my experience that Expiration date is just a legal formality.
In real world experience I have never had a problem cashing in expired tickets.
Not that I have had many but I have found a few worth a few hundred dollars that were 6 months or more expired.

I suppose they could fight it but I doubt it.
I don't think you would have a problem cashing in any ticket from this current problem.
Even if they go out of business they will give everyone time to cash in old tickets, chips and such.
Just my opinion though.