Except I'm not wrong @goldenratio.
Where is the evidence that the media companies you mention or refer to are getting smaller or will do so?
Your suggestion that subscription based services will rise and rise also supposes a larger disposable income than most people have.
Netflix £9.99 for family
Spotify £14.99 for family
Prime, £7.99, (don't know the family price)
Sky & BT Sports £50+, (given the necessary extras)
You're already over £90 per month with the license fee to cover your television, music and sports subscriptions, and you think people will pay even more in order to watch content from ITV, Channel 4 and Channel 5?
And who's to say they won't still have to carry advertising, Sky channels, BT channels, all subscription only channels, and all of them carrying a ton of advertising across all the mediums in which they operate, be it traditional or online.
What will happen in the subscription streaming space is that Netflix, Amazon and the major media companies will dominate and gobble up all the little players who don't fade into obscurity, (which most will because the user experience is really bad), or which appear to be becoming a threat.
And that'll happen because they're already dominant, and people have a finite amount of money and they'll do pretty much anything to maintain their dominance. And they'll succeed too. Just as they always have.
Finally, humans may be mad, but they're not unpredictable, they're actually incredibly easy to predict for the most part, and becoming increasingly so. And business, of the kind which we are talking about is even easier to predict.
Unless something catastrophic happens to any of the companies you mention, they'll still be dominant come the end of our lifetimes.
It's such a safe bet that I doubt bookies would even offer odds on it because it basically translates to a guaranteed loss for them.
Anyway, find and watch that "Fortysomething" show I told you about, take your mind off all this crap. I just rewatched episode one and it really is a most excellent show, lol