I would argue it's a recompile in the same sense that moving a c-based, command line only, project from OSX to Linux is a "recompile". It will most likely kind

I would argue it's a recompile in the same sense that moving a c-based, command line only, project from OSX to Linux is a "recompile". It will most likely kinda work assuming you only touched the most fundamental API calls but the devil is in the details and those are different. Even if we constrain ourselves to pure "digital" designs that somehow magically meet timing perfectly there will still need to be significant changes in architecture to the chip. For example, presumably you went to the lower process node to up the transistor density. This will have serious impact on how charge and heat flow in the design so those systems are going to need a serious overhaul no matter what the RTL was. This is going to impact the layout and the area constraints which is likely going to ripple into the RTL hierarchy. That said, the article's estimates all seem a bit high to me but it's impossible to be certain as they don't specify any of their terms. Is, say, a pipelined ADC in 28nm CMOS a "chip" in their book?