The experience of a subjective thread of consciousness - let's call it STC - is pretty much the experience of experience, or qualia. So Chalmers' experiment is apt.

The relevant fact is that STC is purely subjective. The reason I think you and everyone else have STCs is because you say you do, and it's a simpler hypothesis than the one saying I'm different from everyone else. But the reason I think I have an STC is completely different: I know it from direct experience, which is pretty much by definition incontrovertible. (I may be mistaken about the real world, my experience may not match reality, I may even have false memories, but I can't be literally mistaken about what I'm experiencing right now. Unless you suppose I constantly have false memories of the last half-second and that the induction hypothesis is therefore inapplicable to subjective experience.)

So yes, I can imagine a universe without STCs. By construction, I won't exist in that universe. This is exactly the same question as: can I rule out that no-one else but me in this universe has STCs, or qualia, or consciousness? No, I can't; I can't test the suggestion. But I also can't proceed to the idea that I have no STC, because that would be denying my actual moment-to-moment experience. It would be as pointless as saying I'm colorblind when I'm not.

So to recap, I have no idea how to solve the hard problem of consciousness. I have no idea how to explain the subjective experience and connect it to the objective world, or to test for subjective experiences in somebody else. But I can't pretend consciousness and experience don't exist, either, at least not for me. I hope someone comes along and solves these problems and explains the solution to me - I don't know if this is actually possible, but I hope so - but lack of a solution doesn't make me ignore the problem.