I have both Amazon Prime and Netflix subscriptions, and I also have some video I've purchased on iTunes. I just found out today that Amazon Prime has season 9 of "Bones", but Netflix only goes to season 8. There are also shows leaving Netflix periodically. The first company that creates software which aggregates multiple instant video providers into one player and lets me concentrate on finding the content I want without having to look at 3 different websites will have my money. Plex is really close. If you can figure out how to get the complete list of all the content on each provider, you could provide a feed for all your users based on which services they subscribe to. It would be nearly nirvana if I could come home at night and have my Plex server tell me what new episodes of my favorite shows are available to watch.
As an alternate to a perfect world, it would make my life much simpler if Plex could get streaming video from Amazon, Netflix, Hulu, Apple, and WatchESPN and redirect it to whatever device I want to watch it on. Right now, I have an Apple TV for iTunes and WatchESPN, a bluray player for Amazon Prime, Hulu, and Netflix, ChromeCast for Netflix on the kitchen TV, and separate apps for Amazon, Apple, and Netflix on my iPads, iPhone, Windows phone, and Android phone. Basically, I have to know which service has the content and then figure out how I'm going to access it. It would be sooooo much easier if Plex could redirect video streams to DLNA devices, the Plex app on my mobile devices, or even Chromecast.