Citation needed on that cost effectiveness estimate, but regardless, all infrastructure is incrementally rebuilt and replaced over the years. So instead of eventually building replacement coal [1] plants with fancy (and leaky) CC, we could as well build different plants that don't emit any CO2.
[1] or natural gas, which is what's been happening over the past 10-15 years in the US, primarily because natural gas became cheaper. Those natural gas plants produced less CO2 than coal, which has primarily driven any reduction in the US's CO2 output. But natural gas still produces huge amounts of CO2 and will never be carbon neutral.