although Reggie Fils-Aimé has said that in the future it will be here i honestly believe it will get her before years end. and i quote "At launch we are really trying to be clear that this is a gaming device first, so you're actually not gonna see a lot of that at launch. It doesn't mean that it's not going to come later on, but it likely won't be there at launch." makes me think that when they start to charge for the online we should see both VC and at least Netflix Hulu and probably Amazon at the minimum
Yes, I think it will definitely end up having YouTube and Nextflix eventually like the WiiU did. Lots of people used those, and both platforms have extremely accessible developer APIs that would make it easy for any programmer to do on just about any device, which is why you get those two apps on so many devices compared to all the other types of video apps.
Hulu or Amazon I'm not sure (but I don't use those anyway for videos, so I don't really care so much about those).
While it would be awesome to be able to just do what the original poster said in terms of just slapping in an SD card with videos on it from something else and play it that way, this unfortunately I don't think will ever happen, as in order to be able to read the SD card on those consoles, the SD card always has to be formatted in a way that is specific to that console. (which means that anything else on that SD card gets automatically wiped off it). So that one ain't gonna happen I'm afraid. (shame though)
While the formats that both consoles use though are technically often still standard ones (I think its either FAT16 or FAT32, I can't remember now, it's been a long while since I did it), while this would make it still technically possible, I don't think Nintendo would ever want you doing it due to virusware potentially getting on the console from say a PC download, that had malware etc which could infect your Switch (which one of the reasons why they make you do the formatting for those two consoles via the console itself).
Additionally, when an SD card is formatted for use on one of those consoles, they also put in an extra security layer when they format it which stoops it even being read from a PC to stop you pirating their games. (3DS actually lets you view the files on the PC though, but not for WiiU or Switch). So I expect that is the way it will stay for those consoles.
I do look forward to Netflix coming on it though, so I hope that's sooner rather than later. It's one that I often find useful, and will be even more useful on the Switch than it was on WiiU (with the Switch being portable), as it will mean I can watch Netffix on a bigger screen on the go than how I do it when watching from the Nextflix app on my phone.