Have not been a fan of periodic leases but we will go this way on an investment property as the tenant has advised with their lease up they are looking at other properties that fall within the preferred school catchment area for their children They have been good tenants They originally asked us for a 6 month renewal to allow them time to save up a bond for another rental property in a more suitable location for their children's schooling, once their application is accepted they will advise us, thus they wish to enter into a periodical lease as opposed to a 6 month lease. They will continue to pay current rent (above market) once we lose them the rent will drop a new tenant will be harder to find in the current market, however 'such is life'
If tenant's are harder to find in the current market it sounds like it's a better situation than losing them straight away so look at the up side. You could always enter into a new 6 month lease with them that includes an option for them to terminate on notice. This means you have greater control over the notice period (preferably 4 weeks) which will assist you in finding your new tenant.
I usually recommend shorter 3 month leases for situations like these. You still maintain a measure of control but they're not locked into something long. Think that might work in this situation?