Symbian Foundation is starting on a path to a brave experiment on the importance of a catalogue of applications in the mobile phone space.
The Symbian^4 release of the platform will break compatibility in a big way.
What does this mean?
Applications built for the 100m+ devices on Symbian before the ^4 release will cease to work, and developers will need to rewrite parts of their applications for new devices.
This is a brave experiment by the Symbian Foundation. While undoubtedly it will create open space to make great products by getting rid of legacy, it does level the playing field with other new entrants in the market. Symbian^4 devices will be a new platform, just as iPhone, Android, LiMo, Palm WebOS devices were when they first launched - so they better be great devices to attract developers.
Traditionally "consumer" platforms have been successful if they have maintained compatibility - Microsoft Windows is the iconic example of this, as each release software from the previous few releases - and with release cycles in 3-4 year windows, this means that 10 year old software continues to work. Other platform providers have learned from this - Apple provided an excellent compatibility story for consumers in moving from traditional MacOS to OS X and then from PowerPC to Intel architectures. Similar examples can be seen in gaming consoles from Sony (PlayStation) and Microsoft (XBox) and Nintendo (Gameboy -> Nintendo DS)
There are other examples where devices have chosen to break compatibility - and failed as they haven't attracted the software catalogue and consumers have chosen other devices as they cannot take advantage of their back catalogue of software. Sega's transition from the successful MegaDrive to the Sega Dreamcast was not successful for them.
Developer adoption is more mixed - developers will move to a new platform that provides them with sufficient advantages - the success of new product & platform introductions such as iPhone, Java demonstrate this. Once on the platform developers do expect a continued level of compatibility - developers don't value having to rewrite old code. Successful software platforms such as Java and Flash have understood this, and provide managed solutions to allow developers to reuse old code without changes - but when adding new code take advantage of new features.
There is one particularly pertinent piece of history here. Symbian has broken application compatibility once before.
In the transition from "EPOC" a PDA operating system that delivered high performance on 2 AA cells and a 18Mhz ARM7 core - Symbian moved to only supporting Unicode for mobile phones.
This meant that all software written for the old PDA products needed to be rewritten.
What happened then? The main licensee, and the originator of Symbian, Psion never made the transition to unicode products, and ultimately switched to producing Windows CE based products only.
So if history repeats itself with Symbian^4 with Nokia in the role of Psion, I would predict that future Nokia devices will be based on a non Symbian platform.
Of course there may be another lease of life for Symbian after Nokia - just as there was for Symbian after Psion.
A brave experiment indeed.