I currently use Amazon Prime and Hulu+ primarily. Once the fall shows start (this month), I regrettably have to get CBS All Access. I also watch Crackle (free), Pluto.TV (free), and B/W TV for background noise (free), Occasionally we'll get Netflex and do some binge watching, and then cancel. As for other shows, I'm going to have to pay for Doctor Who episodes ($23/season), but that's cheaper than getting cable that has BBC America.
Overall, this is not the perfect solution. I don't have access to CNN or FoxNews, etc., You don't have a central "DVR queue" that everything you want to watch is in. You also don't always know when new episodes are available, nor where to watch them at. So I've been tempted to get a Tablo or Simple.TV device, which would negate the need for Hulu+ and CBS All Access. Other benefits would be multiple users can stream at the same time, and I can DVR any show I see on the guide (sports, news, award shows, etc.)
Hulu+ needs to allow multi-user streaming, and get CBS content. That would be more important than Epix and AMC. Another win for Hulu+ would be an add-on charge that let you watch USA, etc., without a cable subscription.
CBS AA burns me up, that they want $6/mth when Hulu+ is $8 and includes ABC, Fox, and NBC, and its one location. I never could get CBS on demand on my cable DVR either.
SlingTV would be a better valued service if you could use it to login to the AMC, Cartoon Network, FoxNow, etc. Roku apps as you had stated. I'd love to be open to open the Disney XD app on my Roku and use a SlingTV account to authenticate. That would help with SlingTV only allowing a single stream.
Article notes: You didn't mention that Epix was coming to Hulu soon, and HBO Now is currently available on the AppleTV and FireTV (soon for Roku.)