I gotta say that having experienced some ads on Prime now (got the promo for shipping purposes while buying at Christmas and the month extended into Prime with ads) and all the doom and gloom over it... I'm rather unimpressed. Right now it's basically just a few segments over a show/episode that shows only one commercial that is just showing TV shows for one of the subscription channels, and its the same one over and over again.
Not that I would put any faith in advertisers/marketing people, but while it may not have seemed like it for the longest time it is a profession that grows and adapts with the times. In 'ye olden days' the primary sources for advertising was basically sponsorship, print, and TV commercials. Sponsorship is still their, print is pretty much dead, and while commercials are still kicking around at the same time people started cutting cable they also started carrying smart phones around with them everywhere and openly using social media, and I suspect this is where all the focus has shifted to.
While you can't do the damage that's been done to cable TV still where commercials grew to be about 1/3rd the run time of a show, I really doubt anything like that is going to happen to streaming services. The nefarious marketing/advertising schemes of the future is probably more stuff like putting a 'smart' fridge in peoples kitchen that's connected to your smart phone/social media data listens to what you're saying and makes targeted 'suggestions' on what you should buy for dinner.