The lack of EICAS/ECAM technology isn’t as important as the fixing poor critical systems sensors and failure modes. However, since the Boeing QRH has been dumbed down while retaining its frankly bizarre formatting the timely management of non-normals is not assured for all crews.
The first things that need to be fixed are systems design, then sensors followed by unambiguous displays.
I don’t think they can certify a 737 under the new rules period, and not just because of EICAS integration.