Heikki Linnakangas is one of the top Postgres contributors of all time, he isn't just "someone." The fact he's working for a startup on a fork (that already exists, which you can run right now on your local machine) doesn't warrant any snide dismissal. Robert Haas admitted that it would be a huge amount of work and that it would only be achievable by a small few people anyway, Heikki being among them.

Anyway, I think there are definitely limits that are starting to appear with Postgres in some spots. This is probably one of the most difficult possible solutions to some of those problems, but even if they don't switch to a fully threaded model, being more CPU efficient, better connection handling, etc will all go a substantial way. Doing some of the really hard work is better than none of it, probably.