I agree there is no complete evidence of a full WSI yet. There are several recent papers on Wafer Scale Integration (WSI) and some WSI built (large sensors) with reasonable yields. There are many papers on partial problem solutions that, if combined in one project would yield a full working WSI with existing 7nm standard CMOS process. There are silicon interconnect fabric (SiIF) which is one step removed from a full WSI. There are many commercial chips 1/70th the size of a WSI already and some unpublished WSI results.