Please, Devs, give us as much warning as possible if Landmarks require current in-game resources of any kind.
I know it's a whole meme about how landmarks are coming soon™ but given the permanent nature of landmark ownership (once won, a landmark is yours forever unless your account is deleted or you voluntarily choose to put it back up for auction), please give us as much warning as possible if landmark auctions will require ABs or anything else players can currently stockpile.
The optimal strategy for many (not all!) players is to spend resources as soon as you earn them. It would feel pretty bad if landmarks finally launched, only for most of the player base to be caught flatfooted with no ammo to win any auctions because a whale bought a ton of ABs that morning.
It would feel equally bad if someone hoarded a bunch of resources in anticipation of landmarks, only to find out they could've taken that mayorship or made that tier jump all this time and delayed it for no reason.
TL;DR - Please tell us ASAP if we should consider saving up for landmarks in some form or fashion if we want to be competitive at the start.