Rules when someone buys the flat you rent

Do you have a standard Belgian contract (Main residence - 9 years duration)?
If yes, since the new laws of 2007, your landlord had the legal obligation to register it to protect your rights as tenants for at least, 9 years.

That means that IF the contract has been legally registered and the rented property would be sold, the new owner has the legal obligation to respect your rental contract.

So you can't be evicted!!