Well, that's a complex topic that can't possibly be done justice to in a brief comment. But to put it as succinctly as possible, modern governments are already so powerful that given the existing means at their disposal, additional surveillance won't change things much. Your argument can in fact be used to argue against its relevance -- all the sundry 20th century totalitarians had no problem doing what they did without any surveillance technology to speak of.

My view, which would take much more space than is available here to support by solid arguments, is that the modern Western system of government will continue sliding gradually along the same path as now, determined by bureaucratic inertia and the opinions fashionable among high-status groups; both these things are fairly predictable, as far as any large-scale predictions about human affairs go. Whether these developments should be counted as good or bad, depends on many difficult, controversial, and/or subjective judgments, but realistically, even though I'm inclined towards the latter view, I think anyone with a little prudence will be able to continue living fairly comfortably under the government's radar for the foreseeable future. Even in the conceivable scenarios that might end up in major instability and uncertain outcomes, I don't think surveillance technology will matter much when it comes to the trouble that awaits us in such cases.

On the other hand, I see a very realistic prospect of social norms developing towards a zero-privacy world, where there would be no Orwellian thought police coming after you, but you would be expected to maintain a detailed public log of your life -- theoretically voluntarily, but under the threat of shunning and unemployability in case you refuse it. Already, employers, school admissions bureaucrats, etc. are routinely searching through people's trails left on Facebook and Google. What happens when an even greater portion of one's life will be customarily posted online? How long before not having a rich online trail is considered weird and suspect by itself?

Already, an easily googlable faux pas will be a horrible millstone around your neck for the rest of your life, even if the government couldn't care less about it. What will happen when far more stuff is online, and searchable in far more powerful ways?