WEM will definitely draw people, but while it does employ a lot of people, my hunch is that you're still going to get more people on the Valley Line from Meadowlark going to Downtown (or Oliver, which is basically an extension of Downtown) than WEM on a Tuesday morning.
Sure there's the Mis, but Metro Line already has the Royal Alex and the VLSE has the Grey Nuns. And while Health Sciences does see significant commuter traffic, the number of people getting off there vs University Station most of the time is still significant.