One thing to bare in mind with the modulars is that even if they don't make a huge profit, they do get adults interested in Lego that perhaps otherwise wouldn't be (like myself - I have no interest in 'role play' or minifigs, but I do appreciate the techniques and 'style' of modular buildings). Many of those adults will have children who will then be introduced to Lego, and probably encouraged.
I have certainly encouraged my children to engage with Lego more - and of course it's me that pays for it.
So, it shouldn't be underestimated how much of a 'halo effect' the modular line has on the other lines.