Ca. 1960s (I'll have to dig up some links from Eric Fischer's Flickr later on)...
part of the Route 230 proposal (the Hunter's Point Freeway/Route 87 extension) that would have connected today's Cesar Chavez (Army) Street and I-280 junction southwards towards the Bayshore Freeway in Brisbane...included an extension of Geneva Avenue from its current terminus at Bayshore Boulevard/historic Bypass US 101 in Daly City (originally the town of Bayshore) to where the 230/101 junction would be.
After the Freeway Revolt, 230 has remained on the books (as a proposed, but likely to be unconstructed highway)...but only from 280 to 101 with no mention of a Geneva Avenue connector.
Looks like the proposals to finally connect the T Third MUNI Metro line with the existing Bayshore Caltrain station in Brisbane generally also involve finally linking Geneva to 101 (via the Candlestick Park exit, which would be reconfigured into a simple diamond) decades after it was first thought of:
http://www.sfcta.org/sites/default/files/content/Planning/Bayshore/Bayshore_final_report.pdf