the figures are from PAMA so presumably accurate. The khyber-Cultus analogy is flawed since Khyber model was killed with the launch of Cultus. Also Cultus is a much better shape than Khyber.
Its good to have the opinion of someone who actually owns the car. I also tend to agree with your statement that it isn't really "hated" but also not a likable shape either.
So I guess the question will come down to choice in the range. Cultus survived (rather dominated) the competition from Suzuki's own Alto and also Cuore, and Santro. WagonR is currently having little to no competition save Cultus which is outselling the WagonR. If they kill Cultus for whatever reason (e.g. problem in importing parts), then there is no option but WagonR. Even if Cultus is not killed, there is enough room for 2 to survive. However, can WagonR survive in the event of a another small car entering the market?
There is no imminent danger but who knows. 2-3 yrs down the lane would be a good time to know if its a success, just surviving or a flop.