Really, with more sailings and major improvements to the terminals at Tsawassen and Swartz Bay, the ferry system will be good enough for the next 30-40 years. Those who live on the island likely aren't in any rush.
As for a new bridge "resolving" any of the traffic/congestion/line-up issues at the terminals whenever a ferry breaks down or when there's a storm, think again. You're likely gonna have car crashes on any crossing, which will obviously block traffic and will take time to remove the cars. As well, the crossing will likely be closed whenever there is a storm....which happens on the Confederation Bridge, and of course BC Ferries has major sailing delays whenever that happens.
The ferry route is also a huge tourist attraction....with a bridge, there's nothing to see. Like the Confederation Bridge, a more than one metre high concrete barrier wall protects both sides of the bridge from wind.