I think the EU will have to bear the cost and make the Foundries for whatever high the cost. This matter is now clearly a geopolitical and national security issue (thanks Trump..) and Not an economic issue.They may hope so, but extremely unlikely as Chinese and Korean and somewhat Japanese will have that advanced node chip manufacturing facilities, just a matter of time
Also they are already way more advanced than EU, even Chinese is .. and can produce more cheaply
So even if they need to subsidise these foundries then they would still be committed to constructing them