That's what I think would happen - the tenancy remains for the 6 years or whatever, but at the limited rent.Right. A nightmare situation would be where the tenancy agreement is considered valid but the rent is RTB limited.
This will likely happen when a landlord rents after March. From the Housing Committee, it seems that 'market' rent for a new tenant isn't actually that. It is sort of a reference rent/what the RTB thinks type system. So you're a large landlord, you rent to a tenant at market, that gets reduced but the permanent tenancy remains. You can increase the rent again in 6 years time, but that'll be limited again to this what the RTB thinks type system and/or there will be political interference.
You end up with a sitting tenant for life at a low rent and you're on the hook for all repairs and improvements. An outright disaster. Plus if the tenant is difficult, the stress of the whole thing could take years off your life. Anyone renting after March needs to be beyond careful.