If we look at Praetoria's map right now, we see claiming land reached 120 out of 150 regions.
This is really good, considering before Land 1.0 (Surveying) was rolled out and 
But still, we have 30 regions unclaimed, and some of them will probably remain like that. It's been well over 2 years since the presale for land, and I wouldn't exclude the possibility that some big whales even forgot they purchased land on Splinterlands, and haven't followed through.
I'm curious how much land will remain unclaimed in the end, if it's less than 10 regions I'd say it's a huge victory for Splinterlands and for the Land Expansion. Even 15 would be a good result I believe.
Anyway, starting from Tuestay (after the maintenance), this unclaimed land won't be eligible for SPS rewards. Even more, those who have claimed their land but don't survey it by that time, will also lose their land SPS rewards until the time when they survey their land.
This is the reference to the Tuesday maintenance window when SPS rewards will be switched to surveyed land only (this fragment is part of another proposal that consults SPS stakeholders on modifying land SPS rewards according to the Land 1.5 whitepaper):
This is obviously a bad thing is you haven't claimed or surveyed your land and won't do it by the time this change goes in effect. Although, if you do it at a later time, you will only lose the land SPS rewards you would have received in the meantime, so it's not the end of the world.
At the same time, this is a good thing is you surveyed your land, as the land SPS reward pool will be shared among fewer players/investors, so the rewards per surveyed plot will grow.