Whether viewing figures are high or low surely depends on what you're comparing it to/what context you're talking?
Do I expect every football fan to be regularly watching the matches which they have access to? No
Do I expect average viewing figures to be greater than the normal average when all matches are behind a subscription? Yes
Records will be beaten, I'm sure. Viewing figures for FA Cup matches on terrestrial TV regularly top Sky coverage, let alone big England tournament matches. So free PL matches should do very well. But yeah, they'll be some who won't tune in at all, or who will tune out as quickly as they tune in.