I don't think any industries in the EU function like keiretsu, and what you're describing certainly isn't it. It's
not the same thing as "just using small companies for everything".
It requires a set of small, interlocking companies, (many of which own pieces of each other and have very tight knit relationships) that form part of a greater supply chain. It requires trust and human relationships.
The set of companies in Shenzhen responsible for the "pearl river delta electronics manufacturing miracle" might be the closest analog we have today.
It is perhaps easier in manufacturing because standardization on interlocking components is easier, but it's by no means impossible in software, and with cloud computing we do have an emerging set of interaction standards (e.g. the S3 protocol).
I don't think that the EU actually will follow this path, because it requires pretty deep technical and economic understanding to follow through and policymakers who are resistant to lobbying from, e.g. SAP, but they certainly could, and the EU has surprised me before with smart policymaking where they clearly listened to experts (e.g. with GDPR).