Given an early decision and a long term plan, the Centurion could have continued. A plant set up to gradually remake the hull, turret and suspension with new engine, gearbox etc. with follow up programmes to up rate the weapons systems and armour which would eventually feed into a new hull to make use of modern armour. Not an all at once factory that would die from a boom and bust cycle but a more modest plant that would continuously but gradually recycle the hulls through up grades as technology moved on. Politically there seems no real problem with separating it into a chassis site, engine/gearbox supplier and a turret/weapons system site if that helps the politicians carry it through.
The economic question is whether it is cheaper to use taxes to promote export earning industry to earn the foreign exchange to buy foreign tanks or to keep the money in the national economic cycle.
The politicians avoiding the ageing of the Centurion fleet left them with a need to do a quick fix when Canada's european trading partners told her to act and act fast. That was the driver when Germany offered to lend Leopard 1s to bridge the gap.
Had the rebuild programme been thought through thoroughly and early then Canada could have had a significant tank industry rebuilding Centurions for existing users and then buying old ones in and rebuilding them for those with a need for economical tanks. BAE in Britain built a 25 year business on buying up old their own old Hawker Hunters, rebuilding and reselling them. Often the same airframe several times. The Canadian Centurion equivalent could take this further by, eventually, being able to rehull them in more modern armour. It would still be a viable model with all the upgrades and few sudden huge capital demands. Maybe even expand to do the same for other tanks for foreign customers. There were surplus M48s, M60s and Leopard 1s coming onto the market in time. The work was well within the capability of Canadian industry and would build a pool of heavy industry and electronic sensors etc. which would support other growth into these areas. Almost as if Canadair had gone for the Lockheed Orion market with the Argus with continual improvements.