Chris, clearly you have been at ISC and the article starts well.
But think of this like an Apollo Moonshot program. When Kennedy announced that the US would land men on the moon before the end of the decade.. well NASA did not have Saturn 5 rockets sitting in a big shed somewhere....
Europe should be pushing the envelope, and constructing an exascale system. We already have outstanding centres in Germany, in Barcelona, and in Switzerland.
The UK of course has EPCC, Daresbury and RAL labs, Met Office
(I would say ECMWF but they're off to Italy) Plus the ARM based Isambard project in Bristol.
I do get your points about the lack of CPU foundries and DRAM foundries in Europe.
but the chips themselves don't have to be made in European territory.
Remember the titanium for the SR-71 was purchased from the Russkies!
I fully think that Europe can bring new ideas to Exascale. Both in hardware and importantly in the software.
And Exascale is power hungry. Maybe we should be looking at locating this thing somewhere near a green energy resource too.