Does linear TV's future lie in marketing on-demand content?

I saw a demo of Kangaroo yesterday and really liked it. It got me wondering about the long-term future of linear broadcast TV.

I wonder whether the linear broadcast's role might one day be as a sort of showreel preview / marketing vehicle for material which is pre-loaded in on-demand space. In other words, broadcast the first episode of a series over and over again on linear in order to pique people's interest enough for them to delve into the on-demand space and gorge themselves on the whole series or series (pl). So for example, one might broadcast just the first episode of Brideshead Revisited at irregular intervals, with the whole series loaded into the archive.

Not sure what to watch on-demand? Switch to linear and see if there's anything good being broadcast (promoted). In that respect linear TV would become more like commercial music radio: playing singles to promote purchase of whole albums and back-catalogues.