Albeit I don't agree with tone of your post, this raises an interesting question: will Naughty Dog continue with their previously established plans and carry on with the development of Jak 4?
In this market, no. Having seen what happened to Ratchet (a game geared toward a similar demographic as will be the yet-unreleased Jak 4) in relation to Resistance, and dwelling on the sales of Uncharted internally,
it should come as no surprise when Naughty Dog announces their new project is 1) a sequel to Uncharted (despite sales, Uncharted has potential "mass appeal" like Gears of War or Assassin's Creed) or 2) a "shooter."
I hope this is not the case as I've been yearning to see more from the Jak series from the moment Jak 3 let the credits
roll, but with the current state of the market, I don't think it will be an economical decision for Sony to fund a title whose appeal is in definite question.
EDIT: Surely, there's a good chance my forcast is incorrect but that's why it is dubbed as such: a forecast.
Feel free to argue against my point.