My biggest fear is in what will be lost in the future. These companies haven’t been around long enough for consumers to know how they will retain media. Will they only keep up licenses on the most popular movies? How will you then ever get a legal copy or access to one of your favorite movies of 30 years ago that nobody else liked?
To be fair that only applies to video. With music there's a wide range of digital, DRM-free, lossless purchasing options available. However I worry that this will become a much smaller niche considering the popularity of streaming.
So no real legal alternatives then considering the paltry number of options you'll have.
Anything post-DVD would be problematic due to CSS and suchlike. Maybe whatever videos you can legally get in Ogg format.
It’s a compromise I’m willing to make under certain circumstances, but ultimately one that bothers me.