If they're never going to add instanced housing, they need to just acknowledge it and put in a proper, safe way to sell/trade houses. These things still happen, it's just risky and likely for someone to end up getting scammed in the process (which a GM then has to handle, and they will.)

As far as trading goes, it still happens, it's just at the inconvenience of people farming placards to get their own houses. It's trivial to use a currently open plot as an intermediate, which just ends up resetting the plot timer.

Pretending these things don't already happen isn't going to stop them from happening. Heck, if SE wants gil sinks, just put in a tax on selling/trading plots via whatever new system. People would still do it because it's a ton safer.