As far as I remember, the MSRP for the 770 and 990 was about the same as the DT900/DT700 are now. But as you pointed out correctly, they are on the market for a very long time. The prices will go down significantly, look at the DT1990. MSRP was 600 Euros, but you can get it for ~430 Euros. And even if beyerdynamic says, it is a discount, it is not because the price is 430 Euros for a very long time now and it won't increase again. Same will be true for the DT900 in a couple of months. At least I think so.I think the big problem is that the price increase on the 700 and 900 compared to the 770 and 990 is actually really substantial, so to defeat the 770's and 990's from a value standpoint is impossible given what we're learning about the difference in audio quality between the generations. This has historically been a thing with the 770 and 990 - their outstanding value. It is sometimes said about affordable headphones that they punch way above their price point - I'd say that's never been more true than with those old Beyers. It seems the new gen falls in an area where they would only be recommended if people didn't like the 770 or 990 but somehow still want a similar Beyer. So.. who would those people be? People who really need a detachable cable? People who don't want to EQ a treble peak? Am I being too harsh?
But you are right, the DT900/DT700 are no real successors, because they sound very different. For me, they sound better because I never liked the Beyer peak, but a lot of people will miss something.