I do not think that synth players should be replaced with anything. Synth players can produce sounds that non- electronic instruments can't and are a specialism in their own right. But if it was a choice between my Bach being performed by a synth player or by an orchestra I'd chose the latter.
Whatever your view is as a drummer/ composer that is fine but on a forum which is supposedly for people who love bass guitars I find it surprising that I'm having to argue that, as amazing as today's music production software is, good quality live bass guitar is better than programmed, and that the role of the bass guitar in live music should be cherished and promoted.