Thanks for your thoughtful replyl. Coupla things:

1. There is a tension between your notion of “parallelizabililty” and the need for the enterprise-wide CSS standards you mention. I would hope that sometime someone could somehow figure out better ways to deal with CSS, be it shadow DOM, auto-prefixing, whatever.
2. Parallelizability is also impacted by the need in your approach as I understand it to manually curate combined CSP policies for all microapps.
3. With regard to legacy apps, in our cases it is not that we want to run legacy apps as microapps in composed architectures because we feel like it; that is our strategy for incremental migration of our legacy apps, and there needs to be at least one flavor of microfrontendery that addresses that need with all that it implies.