It's more like upkeep costs rather than "rent" :)
On DAoC housing, upkeep was 2% of the price of the house, per week. So for a whole year, it would roughly cost the price of the house itself. Upkeep could be paid with cash but also "points" (that you earn in PvP, but for us that could be GC Seals etc.)
In any case, having to pay upkeep cost will be useful in order to remove houses of players who are inactive and free some spaces in the housing area. Even if SE will create new areas every time one is full, it will completely sucks after couple of years, when half of the houses will belong to players who left the game. (Could force house despawn if players are inactive for X months as well, but I love the idea of paying upkeep more.)
