Yes, I believe they can become insulin dependent. I'm treated with insulin, but I doubt, at this moment in time at least, I'd come to any great harm without it, there would be other medical treatments I could consider (and I have certainly deteriorated beyond where I could manage without serious levels of meds), I personally just do rather better on insulin than other meds.
But if the T2's pancreas deteriorates to the stage where it no longer produces sufficient insulin of its own, then that diabetic would indeed become insulin dependent. I believe there are posters here on the forum that are in that situation.