I think the "Classic mode" is really the biggest, most game-changing thing here. There are a whole lot of people who hate GNOME Shell (I am not one of them. I'm not a fan either, but I don't think the shell is a step backwards) and are either staying on the outdated GNOME2 platform or hacking on top of GNOME3 to bring back GNOME2.
This, I think, is a great solution which acknowledges the desire/need, but addresses it in a way that embraces newer technologies ("classic mode" is built on GNOME3, in fact), rather than simply rolling back to older dated ones.
Kudos to the GNOME team for this and the entire release!
I liked Gnome Shell but I have large dual monitor systems and run multiple copies of the same apps. The least worst way of dealing with those has been a taskbar. I tried to use extensions but they broke on every new release as well as having random quirks, so I gave up and use the the legacy mode. I'm hoping the new classic mode actually works well. Example issues I've found before are being unable to reorder taskbar buttons, not bringing apps to the foreground when hovering over their buttons during a drag and drop, not having a usable system monitor (I have no need to sort through 3 pages of candidates on a website) and hiding the message area.
It doesn't make any sense to have in one corner, an out-of-date desktop environment in MATE, and in the other corner, Cinnamon fragmenting things yet further.
I want a "traditional" DE in the GNOME 2 style, I don't feel the need to have a tablet UI on my desktop PC with keyboard and mouse. But I'd rather not have to go back to ye olde software to do this. I'd like GNOME to take into account those of us who want to use the new technologies without pretending our 17-inch monitor is a 7-inch tablet.
After what GNOME developers did with GNOME 3, I wouldn't trust their classic mode one bit. Cinnamon devs clearly understand the UI needs of users, and Cinnamon is already superior to pretty much every DM out there in usability.
I wouldn't go so far as wishing them a speedy demise -- if building something like that makes you happy, who am I to hope that it comes to an end.
I do think that those projects will naturally and healthily die out, or perhaps evolve into other forms and directions. They're good projects, I just don't think they are as needed now as they were pre-3.8. And I think for most people, the basic desire/need to have a GTK2/GNOME2-based experience will largely be satisfied by GNOME 3.8.
This, I think, is a great solution which acknowledges the desire/need, but addresses it in a way that embraces newer technologies ("classic mode" is built on GNOME3, in fact), rather than simply rolling back to older dated ones.
Kudos to the GNOME team for this and the entire release!