RE: 80% of Cineworld US Regal Cinemas Will Open2 Jul 2020 15:35
You're correct, it does appear to be a 2018 T&C document however this is one that is referenced on Cineworld's site when they cite clause 15.2:
15.2 Cineworld will not be liable or responsible for any failure to perform, or delay in performance, that is caused by events outside its reasonable control (Force Majeure Event), including any act, event,non-happening, omission or accident which may be due to the following: (iii) Fire, explosion, adverse weather, snow fall, ice, storm, flood, earthquake, subsidence, epidemic or other natural disaster
Their site themselves state that they will continue to take annual membership fees and will seek to credit an extension of time. Thus it is reasonsable (as you say without knowing the actual membership numbers in the state of CA) to accept they will still be in receipt of membership fees.
Cineworld have published their FAQ here: https://www.cineworld.co.uk/static/en/uk/blog/cineworld-cinemas-closure-faq-coronavirus-covid-19