Yes 64-bit systems have always needed multiarch (or ia32-libs in ancient times) to run skype, teamviewer, google earth, etc.
Radiotray is the package I miss the most since I installed Plasma 5 -- it is so handy sitting there ready to play at all times. But of course I can chase down my favorite streams and play them with VLC. It's just not as cool and convenient that way.
I assume that further development of Plasma 5, plus the patch for sni-qt for qt5, will eventually bring back the missing functionality.