This is a good contribution to the debate, but I'm not sure it's decisive. You are essentially saying that technology breakthroughs have not driven recent trends in energy use. But isn't the obvious counterpoint that this is precisely because we haven't been sufficiently funding breakthrough research?

You also seem to lean heavily on the "breakthroughs won't happen" argument, without addressing their argument that "if it doesn't happen we're screwed."

What if you're both right? Then we're screwed?

The reason that part of their argument is so relevant is because humans are capable of much more when our backs are against the wall. If the choice is really as stark as "breakthrough technology or mass death/famine," we will work our butts off to find a way. But if regulation can achieve the needed reductions there is much less reason to try that route.

So your argument is a good contribution but I think there are some missing parts.

...the central argument of N&S, from my point of view, is the need for public investment.  Romm is concentrating on the breakthrough technology research part.  But that's only one part of many possible ways to do public investment.  Public transit? retrofitting? solar installations in all government buildings?  Does Romm or any other regulation policy expert ever deal with these issues?  I wish N&S had not let everyone off the hook by providing such a relatively easy target of breakthrough technology

This seems to be a key component of an integrated approach.  Plugging in add on sources of power into the current structure probably won't suffice and will probably just postpone the reckoning.  The current structure based on concentrated, centralized and dense sources of energy will restrict the application of more decentralized, distributed and less dense energy sources.  But some kind of transitional network would be essential.  Making the transformation will will most certainly involve quite closely coordinated public and private efforts.