I'd be very surprised if anything happens, I can't see Canon believing there to currently be a gap in their product line, a C400 for example that could do 4K would effect C500 sales and I just don't see them doing it. You just have to look at the average product life of Canon products to see that they aren't much of an advocate for change if they can still make money off existing lines.
They could always significantly lower model product cost and introduce the C700 and C900...also fill in the gaps with different features. That move could make business sense towards the "retail end of life" of the current models.