It appears that other nuclear reactors are getting into the Cobalt production game. But I'm not sure how much to trust the details of this news report. They are wrong about a number of details quite frankly. Canada's Chalk River reactor does not (to my knowledge) produce 80% of the world's supply of Cobalt-60. It, together with the three other major isotope production reactors does produce 85% percent of the world's Cobalt-60.
The first thing to understand about Cobalt-60 production is that there are not the same problems as with Molybdenum-99 production. Cobalt-60 can be easily stockpiled and stored so that during outages there are no medical crises, because its half-life is about 5 years. That means that its radioactivity only decreases by about 50% after 5 years.
Molybdenum-99 has a half-life of 3 days. That means that after a week its radioactivity is 25% of what it initially was. After a month, it is down to about 0.1%.
So Molybdenum-99 has to be produced and shipped on an almost daily basis in order to ensure a constant supply. Whereas Cobalt-60 can be shipped far, far less often and still maintain an adequate supply.
Cobalt-60 is produced by neutron absorption of Cobalt-59 (see figure below). This can be done a number of ways, the manner I'm most familiar with is how Gentilly-2, Pickering B, Bruce B and Qinshan 1 and 2 do it, where they replace stainless steel adjuster rods with Cobalt-59 rods. This allows the absorber rods to both help control the reactor and produce a useful (and valuable) by-product.
Does it really matter then that an American reactor is getting into the game? Not really, Canada's CANDU reactors will always easily be able to convert to produce Cobalt-60, but for PWRs there has to be a significant modification done that will always cause some pause for concern. Perhaps if that modification can be done cheap enough it will threaten the CANDU dominance of the field.