Russell Beattie has compiled a quite comprehensive list of services and companies that either already exist, or are moving in to fill the gap that will be left behind when Google shuts off Reader.
And there seem to be around 50 of them.
My guess — and it’s a total guess — is that there’s room for one or two successful startups, and around five successful pivots by existing companies. It’s going to be one wild ride once the shutdown actually happens.
Of the 50 or so, probably fewer than 10 will end up being reasonable direct replacements for both Reader’s web interface and never-supported sync API. Half of those will screw up something like scaling or reliability pretty early, or fail to catch enough buzz to be sustainable financially.
So that leaves maybe 3 to 5 serious products that will back-fill the gap that Reader leaves behind in the near-to-mid term.
Just a guess.
(I’m very intrigued to see what the open source community provides in this space as well.)