Is there a need for Sony DSLRs now there's the NEX-7?

I wrote a while back that the then new NEX-3 and NEX-5 'missed the mark', slightly. And I'm still of that opinion as they use the APS-C format sensor - the same used in their DSLRs. While it gives Sony a better ROI I can't see the advantage over a DSLR to the end user. Why run two systems with different mounts? The majority of the lenses are going to have to be the same size. While it's true they can avoid the larger retro-focus designs for shorter focal lengths, Sony seems intent on producing new cameras, with barely any thought to lenses. What's needed are more primes, more pancake designs, and now that they've introduced the NEX-7 (shown above) with a built-in finder, as I suggested they ought to do (I'm not taking any credit), they could really start to appeal to professional users. Indeed, there's no real reason why Sony couldn't drop the Alpha range entirely, providing the EVF was good enough, especially as the NEX mount looks large enough to accommodate a full frame sensor...