I don't think the resolution is the most important part, ExodusS. When I stream even at 360p, I need to upload at a bitrate of at least 1 mb/s, bare minimum, for the stream to be reasonably good quality. At a higher resolution (say 720p) the number will be higher, but probably not a lot higher (I would guess around 2 mb/s). I'm pretty sure mostly everyone should have at least 2 mb/s download.
Even without the ability to change resolutions, if people are on dial-up, they won't be able to watch the stream, period.
Even without the ability to change resolutions, if people are on dial-up, they won't be able to watch the stream, period.