Tenant
As the outgoing tenant, you need to be sure that your liability is absolutely limited with respect to the new tenant. Better still, you may wish to have no ongoing liability at all. We have seen guarantees by outgoing tenants called in where the new tenant does not succeed and stops paying the rent on account of ongoing default by the tenant. This type of indemnity can be very costly is outside the control of the outgoing tenant.
Landlord
A landlord will typically only need to transfer a lease from one tenant to another, (also known as an assignment of lease) known if the tenant requests it. A transfer of lease will present many considerations for a landlord as you will be assessing the merits of a new tenant. There may be existing or other considerations that need to be negotiated or resolved with the new or outgoing tenant.