The "decriminalization" that is the status quo is merely the policy directive that the police decline to arrest and prosecutors decline to send regular users to jail.
There has been lots of evidence that the police very strongly police drug use and regularly confiscate drugs from drug users.
https://thetyee.ca/News/2020/09/18/Police-Drug-Seizures-DTES...
This is one of the core main changes that will be coming from this legislation. It's real decriminalization and the police can no longer confiscate small amounts of drugs.
This is likely a practical precursor to enabling doctors to prescribe a safe supply of drugs so that drug users don't have to rely on toxic street drugs that will kill them.
But beyond that, if police are no longer stopping and frisking drug users to confiscate their drugs, then this should limit risky drug use behaviours which should save lives. Right now people use drugs by themselves quickly to avoid the police. If they're no longer afraid of the police it may increase the likelihood that they use safe injection sites and more public drug use sites where they are safer and can be more easily connected with the health system.