When we will get Plasma 5 stable as default desktop instead of the 4x series? I’ve tried plasma through the standard repositories, but it’s still a bit shaky. Is there any prevision for a due date? Like next OSuse release? lol!
What do you think yourself?
As new versions of software is only added to a new openSUSE version when it is thought to be stable. It depends on the stability of Plasma 5 (which you see at the moment as not stable enough if I understand your post above correctly) at the time the next version of openSUSE is “closed”. Else it has to wait for the openSUSE version after that one. It is as simple as that.
Well, yes, but Plasma5 is already part of the distribution (even in 13.2), and there’s also a pattern to easily install it. So it will be part of the next release as well.
So the question boils down to when Plasma5 will be the default desktop on a fresh installation. And I don’t think there are any concrete plans for that yet.
13.2 has just been released less than 2 months ago, it is not even certain yet when the next openSUSE release will be (i.e. whether it will be 8 months or maybe 12 months again).
But until then, there will be at least 2, maybe 3 or 4, Plasma 5 feature releases, and there are monthly bug fix releases.
So things will definitely look different by then.
But I have to agree with hcvv here:
Why are you even asking when it will be the default, if you say yourself it is still shakey?
KDE4, the desktop, will still be supported upstream until Fall, and most KF5 applications have not even been released yet.
Although it’s of course perfectly possible to use KDE4 applications in Plasma5, so the latter is not really a point for which desktop should be the default… 
In short: it’s too early to say for sure.