It's not going anywhere without funding, unless you believe early KDE 5 circus UI is somehow the best thing ever. And as the others mentioned the nagging popup is once per year.

Both GNOME and KDE are at the state where unmaintained core apps exist the last time I checked. KDE basing itself on Qt offloaded the largest chunk of behind the scenes development from them which is their biggest advantage compared to GNOME.

Wish Pantheon can have more attention, but I digress.

The KDE UI has improved a lot since the early 5.x days (it's already at 6.5), and some of the design people are working on a style overhaul.