Well, that's what i said, that i don't believe they are limited. What i wanted to know and i don't know if it was answered by yoshi is if they will let other players "visit" another player's house. Not that it matters a lot but it's a small detail that i would like to have.
Those questions were actually covered in the last live letter. Houses are part of instanced housing areas which contain manymany multiple, but finite housing "slots". Once such an instance fills up, following houses will be placed in the next (otherwise identical) instance. As demonstrated by Yoshi during the session, you are free to move between those houses. It is not clear whether this includes entering all houses. My personal prediction is that for the latter, you will need the permission of the respective owners.