I don't see how this isn't dispositive on the economics question. That markets (overwhelmingly) choose to build combined-cycle natural gas plants, choose to add the Rankine bottoming cycle, means the marginal cost of the steam turbine is *less* than the marginal cost of the fuel saved by the efficiency gain. That's the case even in the USA; and natural gas elsewhere in the industrial world is integer-multiples more expensive.

The natural gas plants without steam turbines are precisely the load-following plants that run for a fraction of the time (or at a fraction of their capacity); the relative weight of capital vs. fuel costs is inverted. (Or those, like xAI in Memphis, which are rapidly assembled in rushed desperation. I wonder if that will be a trend in the datacenter boom: designs limited, not by costs under normal market conditions, but bottlenecks affecting rushed projects. Nuclear SMR's would seem to be worst at this—the designs they expect to use haven't even been built yet!)