So IF the S2 IS 20,000 Euros or thereabouts, where does that put any possible baby brother -- assuming they get, as they put it "...very lucky"?
Given any R10 will share a lot of the same tech with the S2, its' also going to share a very good percentage of the hardware (and labor) costs -- even more so if it comes out while the S2 is still immature (a big assumption) and thus hasn't recovered a lot of its development costs.
Having more bodies using the same parts, etc will save development costs on the R10 and help recover common R&D costs, but any R10 will be priced relative to that of the S2 - partly by choice and partly out of necessity.
So, a 12,000 Euro R10 vs a 20,000 Euro S2, or how about a 10,000 Euro SLR? Lot of coin for an SLR these days, let alone in 2010/11 - I don't care whose glass you can bolt to the front of it.
The difference between any possible R10 when/if it's released and whatever a D3x/D700x/1Ds_/A9xx is going for at the time will buy a LOT of older R lenses and adapters, spare bodies - not to mention AF Nikon G and Sony/Zeiss glass.