I doubt the Lab will make any significant changes to existing Mainland rules.
On the other hand, they've definitely moved away from allowing new land to be subdivided, joined, etc. That's always been the rule in Linden's "urban" zoned areas such as Bay City, Nova Albion, Nautilus City, etc., and applies to a big chunk of Zindra. Also, of course, Belli and the old Linden Homes continents, and most predictive of anything to be added in future: the Horizons continent. So, basically, they realize that virtual land is most productive when it follows the same practices as Estates, and that just doesn't include microparcels.
If they did anything, I'd favor just banning everything under 144 sq.m. from being set for sale at all, just as they can't appear in Search.They were just a mistake, so let them die out as painlessly as possible.
Networked advertising, qua advertising, has never really been a thing. There have been a few folks who genuinely misunderstood and thought it might be a business, but that's never been why there are microparcels, and most microparcel-based network "advertisers" know darn well they couldn't pay to light the pixels with the eyeballs and clickthrus. It's always been just a cover for land extortion, with a handful of saps who mistook it for actual advertising. There's just no business to be had there.