Bruce, Take a look at the current energy mix. Per the IEA, fossil fuels supply 82% of global primary energy today and are expected ("New Policies Scenario") to supply 75% in 2040. Even in their optimistic "450" scenario--which the IEA itself says we are not on track to achieve--in 25 years coal, gas and oil would still provide 60% of an energy pie that's bigger than today's. So this isn't about stranded assets: no matter how you slice it, coal and other fossil energy will remain in the mix for a long time, albeit with a reduced share of total energy.
CCS provides a way to mitigate directly the impact of energy sources we won't be able to phase out for a long time, for various reasons of scale, cost, reliabiliity, infrastructure, etc. Maybe it turns out to be too expensive, even on an "nth plant" basis, in which case we don't do it and will instead live with the higher emissions. But if we're serious about reducing emissions without kneecapping the global economic growth that's the crucial fuel for such an effort, then it is premature to rule out CCS.