>How do you think LIDAR tech is going to upend our understanding of history?

It isn't, because that isn't how historical study works. Everything you discover using any method is added to what you already know. The most it does is upend people, who either have long-held beliefs about a certain aspect of history, or are crackpots who seize on it as proof their personal (and otherwise unsupported) brand of lunacy is correct and everyone else is wrong. Fruit loops, like Hancock for instance, always talk about totally upsetting established history, because they don't have a single bit of proof for what they believe, and they desperately want some evidence, any evidence, for what has become their individual religion, if not brand.

>Maybe give us a better perspective on those "barbarians" that invaded Rome

If you're talking about Alaric and the Goths, his name was Flavius Alaricus, and he was a Roman citizen. We have plenty of evidence showing Rome didn't 'fall' as commonly thought, and the pop history narratives around it are comprehensively wrong, based on writings that are hundreds of years out of date.

>or possibly cities that were erased before history.

LIDAR is great for finding sites. It's not going to find something that isn't there. This thread shows what LIDAR surveys can find, as an example. It's a fantastic method, relatively fast, surprisingly accurate. But like any method, it has to be used in conjunction with many others, over the course of years, to do patient, careful research to establish new evidence, and add that evidence to what has already been accumulated.

I think it's potentially a big deal in broadening and deepening our knowledge, but I'm less convinced that it's about to upend history as we know it. My impression (and correct me if I'm wrong, I may be overlooking something) is that where evidence has been found for more intensive development than previously identified, it's been among cultures that were already known to have a fairly developed organisational capability, indeed that's often what drew the researchers to the site: the revelations seem to me to be quantitative advances (and important in their own right) rather than an overturning of existing perspectives. Angkor springs to my mind, its urban core found to have been bigger than previously thought and more intricately connected with the surrounding zone of intensive cultivation, but still not the the vast megacity imagined by some: the new information requires us to imagine a more ambitious scale and a more sophisticated regional supply network, but doesn't consign previous perspectives to the scrap-heap.

I actually do think there are towns (or perhaps we should say strongly clustered differentiated settlements) out there waiting to be found in unexpected places (indeed even where they're abundant the distribution suggests we're missing lots), but the ones I have in mind are modest local centres and trading posts strongly integrated with the adjacent territory or with more distant similar locations, which I find more interesting than the higher-profile tribute cities or ceremonial complexes that will doubtless also turn up, because it's the less ostentatious sites that rely on exchange rather than status, hinting at an active economic role and greater regional complexity.

Either way, it's an exciting technology. I'm happy with whatever turns up, even if it's nothing: a negative finding is itself a positive addition to our knowledge (and in fact I wish they were more fully reported: knowing a location's devoid of any unusual feature that might have been there tells us something of value even if it doesn't make the headlines). Let's see what turns up, it's all good stuff. But I'm not expecting any wholesale undoing of our current broad picture: just more to go on will be fine.