Well i witnessed more than one project just up and dump any pretext of supporting KDE3 once KDE4 was announced.
If the APIs were stable, there would not be a need to drop one for the other.
Look at the kernel, there have never been a situation where one have to go "sorry, but i only support X+1 from now on".
Similarly, until the 64-bit version, and that in turn was because of hardware not software, one could run binaries from Windows 3.0 (at least) on present day Windows.
That is the kind of stability i am talking about. That is the kind of stability that get third parties to stay with a platform.
If the APIs were stable, there would not be a need to drop one for the other.
Look at the kernel, there have never been a situation where one have to go "sorry, but i only support X+1 from now on".
Similarly, until the 64-bit version, and that in turn was because of hardware not software, one could run binaries from Windows 3.0 (at least) on present day Windows.
That is the kind of stability i am talking about. That is the kind of stability that get third parties to stay with a platform.