I think people will use Youtube/video, but they will still use Flipnote Studio, because who WOULDN'T wanna make their own cartoons and animations? DSi, DSi XL, and 3DS users will still use it.
I will answer the flash Q - it has week flash - witch means you can't play games online but you can watch videos like YouTube - I also know it has mii's - 3D movies and videos - gyro - AR games - eShop - face raiders - 3DS sound - Activy log - but it does not have flipnote stuidos but it might come the shop after a few months -
you dont have to make a new account theres steps you have to follow you jut gotta tell hatena and proceed from there but hatena is filled with noobs so im not goin back.
that would be nice like yahooemail and all the other famous emails... its like 8gs of space right so why not video recording camera......IN 3D if its not tooo much to ask 4.