Re: "there needs to be at least 100 people affected with damages exceeding $5m"
There are actuarial methods for figuring it out - you can put a static value on $10 a year forever, if you make assumptions about inflation - I made the mistake of trying one of their exams once and it was very clever math that just refused to stay inside my head long enough to pass. ;)
More likely they will pick a sensible-sounding number of years and use that, and if the case wins then they get to have a separate argument over the exact calculation in order to determine the final award. There are likely precedents in other cases that can be looked at - this may even be why Comcast want this in a federal court, as there could be differences in the normal damage calculation methods.