The purchase itself can still close on schedule. The seller and buyer negotiate whether possession is vacant or tenanted, and the deposit, prorated rent and any adjustments get worked out between the lawyers, but the tenancy itself does not end just because the title changed hands.
If the occupant genuinely will not leave after proper notice, that becomes a landlord and tenant dispute handled through the Office of Residential Tenancies, not something a real estate closing can resolve on its own, so buying a tenanted property means buying the tenancy along with it.
A buyer who wants vacant possession needs that written into the offer and a realistic timeline for the required notice, not an assumption the seller will simply hand over the keys. Get your hand-reviewed valuation from Joel Dyck.