No-one who knows could say anything of significance, Chris. You know that, don't you?
I don't think you should give too much credence to the idea that "Adobe has finally figured out how to significantly enhance Lightroom's performance".
Performance isn't a simple thing - it's multi-faceted. One thing I have advocated since day 1 was the ability to browse embedded previews, just like Photo Mechanic. That's one thing they could do, resolving problems in the culling stage of typical workflows. But it would only open up that one bottleneck. Others potential enhancements are specific to other aspects, for example rendering a raw image after lots of dust spot healing. Some are specific to certain cameras (eg I can export JPEGs from DNGs 35% faster than I can export them from the Fuji raw files used to create the DNGs so there must be an opportunity there). More might come from eliminating unnecessary re-rendering of images, so for instance syncing photos to Mobile might also generate smart previews (see below). It's likely to be a whole range of improvements, not one big thing, and targeting a number of bottlenecks.
I'd also question your "finally". If you read Hogarty's post, you'll see that he refers to things they have already been doing to address performance. I call these "what have the Romans ever done for us?". One was the ability to use smart previews in place of the originals. I just wonder how many take advantage of that. Another is GPU acceleration of certain tasks which, at least in my case, has not delivered any obvious value and just seems to expose LR to more driver-related problems (AMD's recent driver update crashed LR on Windows). The trick is probably to join up enough of these fixes to make general progress impossible to ignore. So imagine that syncing to LrMobile also generated those smart previews to speed up adjustment, for example.
The most surprising thing to me is that Hogarty chose to go public. Of course, they might learn something from the whinefest. Or maybe a bit like Trump's Twitter strategy, for a few days no-one will be talking about anything else....
John