I have a similar problem in mind, it could be an SVG served in a web browser, and then instead of frames you would have an event series of updates, kind of like MIDI does for music: turns certain notes on and off at certain times. So I could have a timestamped list of updates to apply to the SVG (move to x / y coordinate, apply this filter, append these childNodes) -- just use CSS transition to interpolate the movement from one coordinate to the next. You could stream these updates from the server at very low bandwidth.
I've never authored SVGs so this might be a dumb question, but couldn't you use CSS keyframe animations for this? You wouldn't get streaming, but what about the rest?
Though as noted there, Chrome recanted on its 2015 attempt at killing SMIL—and it was only ever Chrome that were labelling SMIL as deprecated, no one else does so. Four years after that, I haven’t heard any more talk about killing it. Notwithstanding that, CSS is now able to cover a lot more of the SMIL use cases than it was then.