The figures are true enough. Whether it's BT or Sky you can expect around 300-700k and the odd 1 million. You can see some of these on barb.uk and these type of figures are often reported in articles each year sourced from barb by newspapers. It's the same old same old.
With the Uefa champions league. The 2015 final was only watched by 500k on Sky and 3.5 million on ITV. Sky had also seen a 36% drop in 5 seasons before any BT deal so general interest to watch champions league football is dropping, some of it is down to English teams not doing well but it's also seen to be stagnating around Europe as well.
Regarding the UEFA article, I can see CL football coming back to terrestrial TV. It's more like bonus football for a lot of people in Europe, not something to pay for, even though it's a prestigious competition. The highlights package won't be viewed by a lot unlike F1 highlights at the moment or for the last 25 years English Premier league highlights which generate millions.
That's how I'm sure these deals can keep going, some pay up and the majority will watch the highlights, sponsors are still happy. An English league game could generate 5-10 million views on normal TV but they've been happy with sub 1 million Sky viewers for 25 years.
F1 is the main event so if people carry on tuning in for highlights in the millions then it shall remain until further issues are felt. The acid test is when no races are shown live, do people feel engaged with just highlights.
UEFA CL is a side tournament to the main leagues and going pay only could be detrimental. Also some in Europe want a super league to stop it being second fiddle. This idea has been kicking around for years but recently mainland Europe has been startled by the TV deal the English League has. If you add the Spanish League, the German League and the Uefa Champions league TV deals together, the English League still beats it. The goal is to make a euro super league before certain countries make a mockery.